Skewing of scheduled search queries

ABSTRACT

Techniques for scheduling search queries in a computing environment are disclosed. A search query scheduling system associates a first set of queries with a first skew tolerance, the first set of queries scheduled to be performed during a first period, where the first skew tolerance is based on a duration of the first period. The search query scheduling system reschedules a first subset of search queries included in the first set of queries by skewing the first subset of search queries over a first portion of the first period based on the first skew tolerance.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates generally to computer analysis of machine-generated data and, more specifically, to skewing of scheduled search queries.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the invention can be understood in detail, a more particular description of the invention may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

FIG. 1 illustrates a networked computer environment in which an embodiment may be implemented;

FIG. 2 illustrates a block diagram of an example data intake and query system in which an embodiment may be implemented;

FIG. 3 is a flow diagram that illustrates how indexers process, index, and store data received from forwarders in accordance with the disclosed embodiments;

FIG. 4 is a flow diagram that illustrates how a search head and indexers perform a search query in accordance with the disclosed embodiments;

FIG. 5 illustrates a scenario where a common customer ID is found among log data received from three disparate sources in accordance with the disclosed embodiments;

FIG. 6A illustrates a search screen in accordance with the disclosed embodiments;

FIG. 6B illustrates a data summary dialog that enables a user to select various data sources in accordance with the disclosed embodiments;

FIGS. 7A-7D illustrate a series of user interface screens for an example data model-driven report generation interface in accordance with the disclosed embodiments;

FIG. 8 illustrates an example search query received from a client and executed by search peers in accordance with the disclosed embodiments;

FIG. 9A illustrates a key indicators view in accordance with the disclosed embodiments;

FIG. 9B illustrates an incident review dashboard in accordance with the disclosed embodiments;

FIG. 9C illustrates a proactive monitoring tree in accordance with the disclosed embodiments;

FIG. 9D illustrates a user interface screen displaying both log data and performance data in accordance with the disclosed embodiments;

FIG. 10 illustrates a block diagram of an example cloud-based data intake and query system in which an embodiment may be implemented;

FIG. 11 illustrates a block diagram of an example data intake and query system that performs searches across external data systems in accordance with the disclosed embodiments;

FIGS. 12-14 illustrate a series of user interface screens for an example data model-driven report generation interface in accordance with the disclosed embodiments;

FIGS. 15-17 illustrate example visualizations generated by a reporting application in accordance with the disclosed embodiments;

FIG. 18 illustrates a block diagram of an example data intake and query system that includes a search query scheduling system and multiple search heads in accordance with the disclosed embodiments;

FIG. 19 is a more detailed illustration of the search query scheduling system of FIG. 18 in accordance with the disclosed embodiments;

FIGS. 20A-20B illustrate example chronographic schedule strings related to search queries in accordance with the disclosed embodiments;

FIG. 21 illustrates example allow skew settings related to search queries in accordance with the disclosed embodiments;

FIGS. 22A-22B illustrate example visualizations of system load before and after search query skewing is enabled in accordance with the disclosed embodiments; and

FIG. 23 is a flow diagram of method steps for skewing search queries in accordance with the disclosed embodiments.

DETAILED DESCRIPTION

Embodiments are described herein according to the following outline:

-   -   1.0. General Overview     -   2.0. Operating Environment         -   2.1. Host Devices         -   2.2. Client Devices         -   2.3. Client Device Applications         -   2.4. Data Server System         -   2.5. Data Ingestion             -   2.5.1. Input             -   2.5.2. Parsing             -   2.5.3. Indexing         -   2.6. Query Processing         -   2.7. Field Extraction         -   2.8. Example Search Screen         -   2.9. Data Modelling         -   2.10. Acceleration Techniques             -   2.10.1. Aggregation Technique             -   2.10.2. Keyword Index             -   2.10.3. High Performance Analytics Store             -   2.10.4. Accelerating Report Generation         -   2.11. Security Features         -   2.12. Data Center Monitoring         -   2.13. Cloud-Based System Overview         -   2.14. Searching Externally Archived Data             -   2.14.1. ERP Process Features         -   2.15. IT Service Monitoring     -   3.0. Skewing Scheduled Search Queries

1.0. General Overview

Modern data centers and other computing environments can comprise anywhere from a few host computer systems to thousands of systems configured to process data, service requests from remote clients, and perform numerous other computational tasks. During operation, various components within these computing environments often generate significant volumes of machine-generated data. For example, machine data is generated by various components in the information technology (IT) environments, such as servers, sensors, routers, mobile devices, Internet of Things (IoT) devices, etc. Machine-generated data can include system logs, network packet data, sensor data, application program data, error logs, stack traces, system performance data, etc. In general, machine-generated data can also include performance data, diagnostic information, and many other types of data that can be analyzed to diagnose performance problems, monitor user interactions, and to derive other insights.

A number of tools are available to analyze machine data, that is, machine-generated data. In order to reduce the size of the potentially vast amount of machine data that may be generated, many of these tools typically pre-process the data based on anticipated data-analysis needs. For example, pre-specified data items may be extracted from the machine data and stored in a database to facilitate efficient retrieval and analysis of those data items at search time. However, the rest of the machine data typically is not saved and discarded during pre-processing. As storage capacity becomes progressively cheaper and more plentiful, there are fewer incentives to discard these portions of machine data and many reasons to retain more of the data.

This plentiful storage capacity is presently making it feasible to store massive quantities of minimally processed machine data for later retrieval and analysis. In general, storing minimally processed machine data and performing analysis operations at search time can provide greater flexibility because it enables an analyst to search all of the machine data, instead of searching only a pre-specified set of data items. This may enable an analyst to investigate different aspects of the machine data that previously were unavailable for analysis.

However, analyzing and searching massive quantities of machine data presents a number of challenges. For example, a data center, servers, or network appliances may generate many different types and formats of machine data (e.g., system logs, network packet data (e.g., wire data, etc.), sensor data, application program data, error logs, stack traces, system performance data, operating system data, virtualization data, etc.) from thousands of different components, which can collectively be very time-consuming to analyze. In another example, mobile devices may generate large amounts of information relating to data accesses, application performance, operating system performance, network performance, etc. There can be millions of mobile devices that report these types of information.

These challenges can be addressed by using an event-based data intake and query system, such as the SPLUNK® ENTERPRISE system developed by Splunk Inc. of San Francisco, Calif. The SPLUNK® ENTERPRISE system is the leading platform for providing real-time operational intelligence that enables organizations to collect, index, and search machine-generated data from various websites, applications, servers, networks, and mobile devices that power their businesses. The SPLUNK® ENTERPRISE system is particularly useful for analyzing data which is commonly found in system log files, network data, and other data input sources. Although many of the techniques described herein are explained with reference to a data intake and query system similar to the SPLUNK® ENTERPRISE system, these techniques are also applicable to other types of data systems.

In the SPLUNK® ENTERPRISE system, machine-generated data are collected and stored as “events”. An event comprises a portion of the machine-generated data and is associated with a specific point in time. For example, events may be derived from “time series data,” where the time series data comprises a sequence of data points (e.g., performance measurements from a computer system, etc.) that are associated with successive points in time. In general, each event can be associated with a timestamp that is derived from the raw data in the event, determined through interpolation between temporally proximate events having known timestamps, or determined based on other configurable rules for associating timestamps with events, etc.

In some instances, machine data can have a predefined format, where data items with specific data formats are stored at predefined locations in the data. For example, the machine data may include data stored as fields in a database table. In other instances, machine data may not have a predefined format, that is, the data is not at fixed, predefined locations, but the data does have repeatable patterns and is not random. This means that some machine data can comprise various data items of different data types and that may be stored at different locations within the data. For example, when the data source is an operating system log, an event can include one or more lines from the operating system log containing raw data that includes different types of performance and diagnostic information associated with a specific point in time.

Examples of components which may generate machine data from which events can be derived include, but are not limited to, web servers, application servers, databases, firewalls, routers, operating systems, and software applications that execute on computer systems, mobile devices, sensors, Internet of Things (IoT) devices, etc. The data generated by such data sources can include, for example and without limitation, server log files, activity log files, configuration files, messages, network packet data, performance measurements, sensor measurements, etc.

The SPLUNK® ENTERPRISE system uses flexible schema to specify how to extract information from the event data. A flexible schema may be developed and redefined as needed. Note that a flexible schema may be applied to event data “on the fly,” when it is needed (e.g., at search time, index time, ingestion time, etc.). When the schema is not applied to event data until search time it may be referred to as a “late-binding schema.”

During operation, the SPLUNK® ENTERPRISE system starts with raw input data (e.g., one or more system logs, streams of network packet data, sensor data, application program data, error logs, stack traces, system performance data, etc.). The system divides this raw data into blocks (e.g., buckets of data, each associated with a specific time frame, etc.), and parses the raw data to produce timestamped events. The system stores the timestamped events in a data store. The system enables users to run queries against the stored data to, for example, retrieve events that meet criteria specified in a query, such as containing certain keywords or having specific values in defined fields. As used herein throughout, data that is part of an event is referred to as “event data”. In this context, the term “field” refers to a location in the event data containing one or more values for a specific data item. As will be described in more detail herein, the fields are defined by extraction rules (e.g., regular expressions) that derive one or more values from the portion of raw machine data in each event that has a particular field specified by an extraction rule. The set of values so produced are semantically-related (such as IP address), even though the raw machine data in each event may be in different formats (e.g., semantically-related values may be in different positions in the events derived from different sources).

As noted above, the SPLUNK® ENTERPRISE system utilizes a late-binding schema to event data while performing queries on events. One aspect of a late-binding schema is applying “extraction rules” to event data to extract values for specific fields during search time. More specifically, the extraction rules for a field can include one or more instructions that specify how to extract a value for the field from the event data. An extraction rule can generally include any type of instruction for extracting values from data in events. In some cases, an extraction rule comprises a regular expression where a sequence of characters form a search pattern, in which case the rule is referred to as a “regex rule.” The system applies the regex rule to the event data to extract values for associated fields in the event data by searching the event data for the sequence of characters defined in the regex rule.

In the SPLUNK® ENTERPRISE system, a field extractor may be configured to automatically generate extraction rules for certain field values in the events when the events are being created, indexed, or stored, or possibly at a later time. Alternatively, a user may manually define extraction rules for fields using a variety of techniques. In contrast to a conventional schema for a database system, a late-binding schema is not defined at data ingestion time. Instead, the late-binding schema can be developed on an ongoing basis until the time a query is actually executed. This means that extraction rules for the fields in a query may be provided in the query itself, or may be located during execution of the query. Hence, as a user learns more about the data in the events, the user can continue to refine the late-binding schema by adding new fields, deleting fields, or modifying the field extraction rules for use the next time the schema is used by the system. Because the SPLUNK® ENTERPRISE system maintains the underlying raw data and uses late-binding schema for searching the raw data, it enables a user to continue investigating and learn valuable insights about the raw data.

In some embodiments, a common field name may be used to reference two or more fields containing equivalent data items, even though the fields may be associated with different types of events that possibly have different data formats and different extraction rules. By enabling a common field name to be used to identify equivalent fields from different types of events generated by disparate data sources, the system facilitates use of a “common information model” (CIM) across the disparate data sources (further discussed with respect to FIG. 5).

The size of modern data centers and other computing environments can vary from a few computer systems to thousands of computer systems. Each computer system in such computing environments is generally configured to process data, service requests from remote clients, and perform numerous other computational tasks. During operation, the computer systems within these computing environments often generate significant volumes of machine-generated data. This machine-generated data may be stored in one or more data stores. These data stores can be accessed via subsequent search and analysis operations for the purpose of finding certain patterns, trends, correlations, and other useful information. One approach for performing such search and analysis operations is to schedule certain search queries to occur periodically. For example, a set of search queries could be scheduled to occur on an ongoing basis at the beginning of each successive search period, such as the beginning of each minute or the beginning of each hour.

One potential drawback with the approach described above is that the computing systems, data stores, and other associated network components encounter a significant increase in demand for computing resources and throughput at the beginning of each search period. Once the search queries have finished processing, the demand for computing resources and throughput demand reduces to a relatively low level until the beginning of the next search period. Further, in cases where the number of scheduled search queries is sufficiently high, such as 200-400 search queries per minute, the computing resources and throughput demand could temporarily exceed the maximum capacity of the computing environment. As a result, data transferred among computing systems and data stores may be lost, leading to incorrect or incomplete results, reduced system performance, and, in extreme circumstances, failure of one or more computing systems, data stores, and other associated network components.

As the foregoing illustrates, what is needed in the art are more effective ways to schedule search queries in computing environments.

Various embodiments of the present application set forth a method for scheduling search queries in a computing environment. The method includes associating a first set of queries with a first search tolerance, the first set of queries scheduled to be performed during a first period, where the first search tolerance is based on a duration of the first period. The method further includes rescheduling a first subset of search queries included in the first set of queries by skewing the first subset of search queries over a first portion of the first period based on the first search tolerance.

Other embodiments of the present invention include, without limitation, a computer-readable medium including instructions for performing one or more aspects of the disclosed techniques, as well as a computing device for performing one or more aspects of the disclosed techniques.

At least one advantage of the disclosed techniques is that search queries scheduled to occur simultaneously are skewed over a period of time. As a result, the demand for computing and network resources is not concentrated at certain instances in time, but rather is distributed over a period of time. By distributing the demand for computing and network resources over time, the likelihood of network data packet loss or other failure modes due to the excess demand is reduced relative to prior approaches.

2.0. Operating Environment

FIG. 1 illustrates a networked computer system 100 in which an embodiment may be implemented. Those skilled in the art would understand that FIG. 1 represents one example of a networked computer system and other embodiments may use different arrangements.

The networked computer system 100 comprises one or more computing devices. These one or more computing devices comprise any combination of hardware and software configured to implement the various logical components described herein. For example, the one or more computing devices may include one or more memories that store instructions for implementing the various components described herein, one or more hardware processors configured to execute the instructions stored in the one or more memories, and various data repositories in the one or more memories for storing data structures utilized and manipulated by the various components.

In an embodiment, one or more client devices 102 are coupled to one or more host devices 106 and a data intake and query system 108 via one or more networks 104. Networks 104 broadly represent one or more LANs, WANs, cellular networks (e.g., LTE, HSPA, 3G, and other cellular technologies), and/or networks using any of wired, wireless, terrestrial microwave, or satellite links, and may include the public Internet.

2.1. Host Devices

In the illustrated embodiment, a system 100 includes one or more host devices 106. Host devices 106 may broadly include any number of computers, virtual machine instances, and/or data centers that are configured to host or execute one or more instances of host applications 114. In general, a host device 106 may be involved, directly or indirectly, in processing requests received from client devices 102. Each host device 106 may comprise, for example, one or more of a network device, a web server, an application server, a database server, etc. A collection of host devices 106 may be configured to implement a network-based service. For example, a provider of a network-based service may configure one or more host devices 106 and host applications 114 (e.g., one or more web servers, application servers, database servers, etc.) to collectively implement the network-based application.

In general, client devices 102 communicate with one or more host applications 114 to exchange information. The communication between a client device 102 and a host application 114 may, for example, be based on the Hypertext Transfer Protocol (HTTP) or any other network protocol. Content delivered from the host application 114 to a client device 102 may include, for example, HTML documents, media content, etc. The communication between a client device 102 and host application 114 may include sending various requests and receiving data packets. For example, in general, a client device 102 or application running on a client device may initiate communication with a host application 114 by making a request for a specific resource (e.g., based on an HTTP request), and the application server may respond with the requested content stored in one or more response packets.

In the illustrated embodiment, one or more of host applications 114 may generate various types of performance data during operation, including event logs, network data, sensor data, and other types of machine-generated data. For example, a host application 114 comprising a web server may generate one or more web server logs in which details of interactions between the web server and any number of client devices 102 is recorded. As another example, a host device 106 comprising a router may generate one or more router logs that record information related to network traffic managed by the router. As yet another example, a host application 114 comprising a database server may generate one or more logs that record information related to requests sent from other host applications 114 (e.g., web servers or application servers) for data managed by the database server.

2.2. Client Devices

Client devices 102 of FIG. 1 represent any computing device capable of interacting with one or more host devices 106 via a network 104. Examples of client devices 102 may include, without limitation, smart phones, tablet computers, handheld computers, wearable devices, laptop computers, desktop computers, servers, portable media players, gaming devices, and so forth. In general, a client device 102 can provide access to different content, for instance, content provided by one or more host devices 106, etc. Each client device 102 may comprise one or more client applications 110, described in more detail in a separate section hereinafter.

2.3. Client Device Applications

In an embodiment, each client device 102 may host or execute one or more client applications 110 that are capable of interacting with one or more host devices 106 via one or more networks 104. For instance, a client application 110 may be or comprise a web browser that a user may use to navigate to one or more websites or other resources provided by one or more host devices 106. As another example, a client application 110 may comprise a mobile application or “app.” For example, an operator of a network-based service hosted by one or more host devices 106 may make available one or more mobile apps that enable users of client devices 102 to access various resources of the network-based service. As yet another example, client applications 110 may include background processes that perform various operations without direct interaction from a user. A client application 110 may include a “plug-in” or “extension” to another application, such as a web browser plug-in or extension.

In an embodiment, a client application 110 may include a monitoring component 112. At a high level, the monitoring component 112 comprises a software component or other logic that facilitates generating performance data related to a client device's operating state, including monitoring network traffic sent and received from the client device and collecting other device and/or application-specific information. Monitoring component 112 may be an integrated component of a client application 110, a plug-in, an extension, or any other type of add-on component. Monitoring component 112 may also be a stand-alone process.

In one embodiment, a monitoring component 112 may be created when a client application 110 is developed, for example, by an application developer using a software development kit (SDK). The SDK may include custom monitoring code that can be incorporated into the code implementing a client application 110. When the code is converted to an executable application, the custom code implementing the monitoring functionality can become part of the application itself.

In some cases, an SDK or other code for implementing the monitoring functionality may be offered by a provider of a data intake and query system, such as a system 108. In such cases, the provider of the system 108 can implement the custom code so that performance data generated by the monitoring functionality is sent to the system 108 to facilitate analysis of the performance data by a developer of the client application or other users.

In an embodiment, the custom monitoring code may be incorporated into the code of a client application 110 in a number of different ways, such as the insertion of one or more lines in the client application code that call or otherwise invoke the monitoring component 112. As such, a developer of a client application 110 can add one or more lines of code into the client application 110 to trigger the monitoring component 112 at desired points during execution of the application. Code that triggers the monitoring component may be referred to as a monitor trigger. For instance, a monitor trigger may be included at or near the beginning of the executable code of the client application 110 such that the monitoring component 112 is initiated or triggered as the application is launched, or included at other points in the code that correspond to various actions of the client application, such as sending a network request or displaying a particular interface.

In an embodiment, the monitoring component 112 may monitor one or more aspects of network traffic sent and/or received by a client application 110. For example, the monitoring component 112 may be configured to monitor data packets transmitted to and/or from one or more host applications 114. Incoming and/or outgoing data packets can be read or examined to identify network data contained within the packets, for example, and other aspects of data packets can be analyzed to determine a number of network performance statistics. Monitoring network traffic may enable information to be gathered particular to the network performance associated with a client application 110 or set of applications.

In an embodiment, network performance data refers to any type of data that indicates information about the network and/or network performance. Network performance data may include, for instance, a URL requested, a connection type (e.g., HTTP, HTTPS, etc.), a connection start time, a connection end time, an HTTP status code, request length, response length, request headers, response headers, connection status (e.g., completion, response time(s), failure, etc.), and the like. Upon obtaining network performance data indicating performance of the network, the network performance data can be transmitted to a data intake and query system 108 for analysis.

Upon developing a client application 110 that incorporates a monitoring component 112, the client application 110 can be distributed to client devices 102. Applications generally can be distributed to client devices 102 in any manner, or they can be pre-loaded. In some cases, the application may be distributed to a client device 102 via an application marketplace or other application distribution system. For instance, an application marketplace or other application distribution system might distribute the application to a client device based on a request from the client device to download the application.

Examples of functionality that enables monitoring performance of a client device are described in U.S. patent application Ser. No. 14/524,748, entitled “UTILIZING PACKET HEADERS TO MONITOR NETWORK TRAFFIC IN ASSOCIATION WITH A CLIENT DEVICE”, filed on 27 Oct. 2014, and which is hereby incorporated by reference in its entirety for all purposes.

In an embodiment, the monitoring component 112 may also monitor and collect performance data related to one or more aspects of the operational state of a client application 110 and/or client device 102. For example, a monitoring component 112 may be configured to collect device performance information by monitoring one or more client device operations, or by making calls to an operating system and/or one or more other applications executing on a client device 102 for performance information. Device performance information may include, for instance, a current wireless signal strength of the device, a current connection type and network carrier, current memory performance information, a geographic location of the device, a device orientation, and any other information related to the operational state of the client device.

In an embodiment, the monitoring component 112 may also monitor and collect other device profile information including, for example, a type of client device, a manufacturer and model of the device, versions of various software applications installed on the device, and so forth.

In general, a monitoring component 112 may be configured to generate performance data in response to a monitor trigger in the code of a client application 110 or other triggering application event, as described above, and to store the performance data in one or more data records. Each data record, for example, may include a collection of field-value pairs, each field-value pair storing a particular item of performance data in association with a field for the item. For example, a data record generated by a monitoring component 112 may include a “networkLatency” field (not shown in the Figure) in which a value is stored. This field indicates a network latency measurement associated with one or more network requests. The data record may include a “state” field to store a value indicating a state of a network connection, and so forth for any number of aspects of collected performance data.

2.4. DATA SERVER SYSTEM

FIG. 2 depicts a block diagram of an exemplary data intake and query system 108, similar to the SPLUNK® ENTERPRISE system. System 108 includes one or more forwarders 204 that receive data from a variety of input data sources 202, and one or more indexers 206 that process and store the data in one or more data stores 208. These forwarders and indexers can comprise separate computer systems, or may alternatively comprise separate processes executing on one or more computer systems.

Each data source 202 broadly represents a distinct source of data that can be consumed by a system 108. Examples of a data source 202 include, without limitation, data files, directories of files, data sent over a network, event logs, registries, etc.

During operation, the forwarders 204 identify which indexers 206 receive data collected from a data source 202 and forward the data to the appropriate indexers. Forwarders 204 can also perform operations on the data before forwarding, including removing extraneous data, detecting timestamps in the data, parsing data, indexing data, routing data based on criteria relating to the data being routed, and/or performing other data transformations.

In an embodiment, a forwarder 204 may comprise a service accessible to client devices 102 and host devices 106 via a network 104. For example, one type of forwarder 204 may be capable of consuming vast amounts of real-time data from a potentially large number of client devices 102 and/or host devices 106. The forwarder 204 may, for example, comprise a computing device which implements multiple data pipelines or “queues” to handle forwarding of network data to indexers 206. A forwarder 204 may also perform many of the functions that are performed by an indexer. For example, a forwarder 204 may perform keyword extractions on raw data or parse raw data to create events. A forwarder 204 may generate time stamps for events. Additionally or alternatively, a forwarder 204 may perform routing of events to indexers. Data store 208 may contain events derived from machine data from a variety of sources all pertaining to the same component in an IT environment, and this data may be produced by the machine in question or by other components in the IT environment.

2.5. Data Ingestion

FIG. 3 depicts a flow chart illustrating an example data flow performed by Data Intake and Query system 108, in accordance with the disclosed embodiments. The data flow illustrated in FIG. 3 is provided for illustrative purposes only; those skilled in the art would understand that one or more of the steps of the processes illustrated in FIG. 3 may be removed or the ordering of the steps may be changed. Furthermore, for the purposes of illustrating a clear example, one or more particular system components are described in the context of performing various operations during each of the data flow stages. For example, a forwarder is described as receiving and processing data during an input phase; an indexer is described as parsing and indexing data during parsing and indexing phases; and a search head is described as performing a search query during a search phase. However, other system arrangements and distributions of the processing steps across system components may be used.

2.5.1. Input

At block 302, a forwarder receives data from an input source, such as a data source 202 shown in FIG. 2. A forwarder initially may receive the data as a raw data stream generated by the input source. For example, a forwarder may receive a data stream from a log file generated by an application server, from a stream of network data from a network device, or from any other source of data. In one embodiment, a forwarder receives the raw data and may segment the data stream into “blocks”, or “buckets,” possibly of a uniform data size, to facilitate subsequent processing steps.

At block 304, a forwarder or other system component annotates each block generated from the raw data with one or more metadata fields. These metadata fields may, for example, provide information related to the data block as a whole and may apply to each event that is subsequently derived from the data in the data block. For example, the metadata fields may include separate fields specifying each of a host, a source, and a source type related to the data block. A host field may contain a value identifying a host name or IP address of a device that generated the data. A source field may contain a value identifying a source of the data, such as a pathname of a file or a protocol and port related to received network data. A source type field may contain a value specifying a particular source type label for the data. Additional metadata fields may also be included during the input phase, such as a character encoding of the data, if known, and possibly other values that provide information relevant to later processing steps. In an embodiment, a forwarder forwards the annotated data blocks to another system component (typically an indexer) for further processing.

The SPLUNK® ENTERPRISE system allows forwarding of data from one SPLUNK® ENTERPRISE instance to another, or even to a third-party system. SPLUNK® ENTERPRISE system can employ different types of forwarders in a configuration.

In an embodiment, a forwarder may contain the essential components needed to forward data. It can gather data from a variety of inputs and forward the data to a SPLUNK® ENTERPRISE server for indexing and searching. It also can tag metadata (e.g., source, source type, host, etc.).

Additionally or optionally, in an embodiment, a forwarder has the capabilities of the aforementioned forwarder as well as additional capabilities. The forwarder can parse data before forwarding the data (e.g., associate a time stamp with a portion of data and create an event, etc.) and can route data based on criteria such as source or type of event. It can also index data locally while forwarding the data to another indexer.

2.5.2. Parsing

At block 306, an indexer receives data blocks from a forwarder and parses the data to organize the data into events. In an embodiment, to organize the data into events, an indexer may determine a source type associated with each data block (e.g., by extracting a source type label from the metadata fields associated with the data block, etc.) and refer to a source type configuration corresponding to the identified source type. The source type definition may include one or more properties that indicate to the indexer to automatically determine the boundaries of events within the data. In general, these properties may include regular expression-based rules or delimiter rules where, for example, event boundaries may be indicated by predefined characters or character strings. These predefined characters may include punctuation marks or other special characters including, for example, carriage returns, tabs, spaces, line breaks, etc. If a source type for the data is unknown to the indexer, an indexer may infer a source type for the data by examining the structure of the data. Then, it can apply an inferred source type definition to the data to create the events.

At block 308, the indexer determines a timestamp for each event. Similar to the process for creating events, an indexer may again refer to a source type definition associated with the data to locate one or more properties that indicate instructions for determining a timestamp for each event. The properties may, for example, instruct an indexer to extract a time value from a portion of data in the event, to interpolate time values based on timestamps associated with temporally proximate events, to create a timestamp based on a time the event data was received or generated, to use the timestamp of a previous event, or use any other rules for determining timestamps.

At block 310, the indexer associates with each event one or more metadata fields including a field containing the timestamp (in some embodiments, a timestamp may be included in the metadata fields) determined for the event. These metadata fields may include a number of “default fields” that are associated with all events, and may also include one more custom fields as defined by a user. Similar to the metadata fields associated with the data blocks at block 304, the default metadata fields associated with each event may include a host, source, and source type field including or in addition to a field storing the timestamp.

At block 312, an indexer may optionally apply one or more transformations to data included in the events created at block 306. For example, such transformations can include removing a portion of an event (e.g., a portion used to define event boundaries, extraneous characters from the event, other extraneous text, etc.), masking a portion of an event (e.g., masking a credit card number), removing redundant portions of an event, etc. The transformations applied to event data may, for example, be specified in one or more configuration files and referenced by one or more source type definitions.

2.5.3. Indexing

At blocks 314 and 316, an indexer can optionally generate a keyword index to facilitate fast keyword searching for event data. To build a keyword index, at block 314, the indexer identifies a set of keywords in each event. At block 316, the indexer includes the identified keywords in an index, which associates each stored keyword with reference pointers to events containing that keyword (or to locations within events where that keyword is located, other location identifiers, etc.). When an indexer subsequently receives a keyword-based query, the indexer can access the keyword index to quickly identify events containing the keyword.

In some embodiments, the keyword index may include entries for name-value pairs found in events, where a name-value pair can include a pair of keywords connected by a symbol, such as an equals sign or colon. This way, events containing these name-value pairs can be quickly located. In some embodiments, fields can automatically be generated for some or all of the name-value pairs at the time of indexing. For example, if the string “dest=10.0.1.2” is found in an event, a field named “dest” may be created for the event, and assigned a value of “10.0.1.2”.

At block 318, the indexer stores the events with an associated timestamp in a data store 208. Timestamps enable a user to search for events based on a time range. In one embodiment, the stored events are organized into “buckets,” where each bucket stores events associated with a specific time range based on the timestamps associated with each event. This may not only improve time-based searching, but also allows for events with recent timestamps, which may have a higher likelihood of being accessed, to be stored in a faster memory to facilitate faster retrieval. For example, buckets containing the most recent events can be stored in flash memory rather than on a hard disk.

Each indexer 206 may be responsible for storing and searching a subset of the events contained in a corresponding data store 208. By distributing events among the indexers and data stores, the indexers can analyze events for a query in parallel. For example, using map-reduce techniques, each indexer returns partial responses for a subset of events to a search head that combines the results to produce an answer for the query. By storing events in buckets for specific time ranges, an indexer may further optimize data retrieval process by searching buckets corresponding to time ranges that are relevant to a query.

Moreover, events and buckets can also be replicated across different indexers and data stores to facilitate high availability and disaster recovery as described in U.S. patent application Ser. No. 14/266,812, entitled “Site-Based Search Affinity”, filed on 30 Apr. 2014, and in U.S. patent application Ser. No. 14/266,817, entitled “Multi-Site Clustering”, also filed on 30 Apr. 2014, each of which is hereby incorporated by reference in its entirety for all purposes.

2.6. Query Processing

FIG. 4 is a flow diagram that illustrates an exemplary process that a search head and one or more indexers may perform during a search query. At block 402, a search head receives a search query from a client. At block 404, the search head analyzes the search query to determine what portion(s) of the query can be delegated to indexers and what portions of the query can be executed locally by the search head. At block 406, the search head distributes the determined portions of the query to the appropriate indexers. In an embodiment, a search head cluster may take the place of an independent search head where each search head in the search head cluster coordinates with peer search heads in the search head cluster to schedule jobs, replicate search results, update configurations, fulfill search requests, etc. In an embodiment, the search head (or each search head) communicates with a master node (also known as a cluster master, not shown in FIG.) that provides the search head with a list of indexers to which the search head can distribute the determined portions of the query. The master node maintains a list of active indexers and can also designate which indexers may have responsibility for responding to queries over certain sets of events. A search head may communicate with the master node before the search head distributes queries to indexers to discover the addresses of active indexers.

At block 408, the indexers to which the query was distributed, search data stores associated with them for events that are responsive to the query. To determine which events are responsive to the query, the indexer searches for events that match the criteria specified in the query. These criteria can include matching keywords or specific values for certain fields. The searching operations at block 408 may use the late-binding schema to extract values for specified fields from events at the time the query is processed. In an embodiment, one or more rules for extracting field values may be specified as part of a source type definition. The indexers may then either send the relevant events back to the search head, or use the events to determine a partial result, and send the partial result back to the search head.

At block 410, the search head combines the partial results and/or events received from the indexers to produce a final result for the query. This final result may comprise different types of data depending on what the query requested. For example, the results can include a listing of matching events returned by the query, or some type of visualization of the data from the returned events. In another example, the final result can include one or more calculated values derived from the matching events.

The results generated by the system 108 can be returned to a client using different techniques. For example, one technique streams results or relevant events back to a client in real-time as they are identified. Another technique waits to report the results to the client until a complete set of results (which may include a set of relevant events or a result based on relevant events) is ready to return to the client. Yet another technique streams interim results or relevant events back to the client in real-time until a complete set of results is ready, and then returns the complete set of results to the client. In another technique, certain results are stored as “search jobs” and the client may retrieve the results by referring the search jobs.

The search head can also perform various operations to make the search more efficient. For example, before the search head begins execution of a query, the search head can determine a time range for the query and a set of common keywords that all matching events include. The search head may then use these parameters to query the indexers to obtain a superset of the eventual results. Then, during a filtering stage, the search head can perform field-extraction operations on the superset to produce a reduced set of search results. This speeds up queries that are performed on a periodic basis.

2.7. Field Extraction

The search head 210 allows users to search and visualize event data extracted from raw machine data received from homogenous data sources. It also allows users to search and visualize event data extracted from raw machine data received from heterogeneous data sources. The search head 210 includes various mechanisms, which may additionally reside in an indexer 206, for processing a query. Splunk Processing Language (SPL), used in conjunction with the SPLUNK® ENTERPRISE system, can be utilized to make a query. SPL is a pipelined search language in which a set of inputs is operated on by a first command in a command line, and then a subsequent command following the pipe symbol “|” operates on the results produced by the first command, and so on for additional commands. Other query languages, such as the Structured Query Language (“SQL”), can be used to create a query.

In response to receiving the search query, search head 210 uses extraction rules to extract values for the fields associated with a field or fields in the event data being searched. The search head 210 obtains extraction rules that specify how to extract a value for certain fields from an event. Extraction rules can comprise regex rules that specify how to extract values for the relevant fields. In addition to specifying how to extract field values, the extraction rules may also include instructions for deriving a field value by performing a function on a character string or value retrieved by the extraction rule. For example, a transformation rule may truncate a character string, or convert the character string into a different data format. In some cases, the query itself can specify one or more extraction rules.

The search head 210 can apply the extraction rules to event data that it receives from indexers 206. Indexers 206 may apply the extraction rules to events in an associated data store 208. Extraction rules can be applied to all the events in a data store, or to a subset of the events that have been filtered based on some criteria (e.g., event time stamp values, etc.). Extraction rules can be used to extract one or more values for a field from events by parsing the event data and examining the event data for one or more patterns of characters, numbers, delimiters, etc., that indicate where the field begins and, optionally, ends.

FIG. 5 illustrates an example of raw machine data received from disparate data sources. In this example, a user submits an order for merchandise using a vendor's shopping application program 501 running on the user's system. In this example, the order was not delivered to the vendor's server due to a resource exception at the destination server that is detected by the middleware code 502. The user then sends a message to the customer support 503 to complain about the order failing to complete. The three systems 501, 502, and 503 are disparate systems that do not have a common logging format. The order application 501 sends log data 504 to the SPLUNK® ENTERPRISE system in one format, the middleware code 502 sends error log data 505 in a second format, and the support server 503 sends log data 506 in a third format.

Using the log data received at one or more indexers 206 from the three systems the vendor can uniquely obtain an insight into user activity, user experience, and system behavior. The search head 210 allows the vendor's administrator to search the log data from the three systems that one or more indexers 206 are responsible for searching, thereby obtaining correlated information, such as the order number and corresponding customer ID number of the person placing the order. The system also allows the administrator to see a visualization of related events via a user interface. The administrator can query the search head 210 for customer ID field value matches across the log data from the three systems that are stored at the one or more indexers 206. The customer ID field value exists in the data gathered from the three systems, but the customer ID field value may be located in different areas of the data given differences in the architecture of the systems—there is a semantic relationship between the customer ID field values generated by the three systems. The search head 210 requests event data from the one or more indexers 206 to gather relevant event data from the three systems. It then applies extraction rules to the event data in order to extract field values that it can correlate. The search head may apply a different extraction rule to each set of events from each system when the event data format differs among systems. In this example, the user interface can display to the administrator the event data corresponding to the common customer ID field values 507, 508, and 509, thereby providing the administrator with insight into a customer's experience.

Note that query results can be returned to a client, a search head, or any other system component for further processing. In general, query results may include a set of one or more events, a set of one or more values obtained from the events, a subset of the values, statistics calculated based on the values, a report containing the values, or a visualization, such as a graph or chart, generated from the values.

2.8. Example Search Screen

FIG. 6A illustrates an example search screen 600 in accordance with the disclosed embodiments. Search screen 600 includes a search bar 602 that accepts user input in the form of a search string. It also includes a time range picker 612 that enables the user to specify a time range for the search. For “historical searches” the user can select a specific time range, or alternatively a relative time range, such as “today,” “yesterday” or “last week.” For “real-time searches,” the user can select the size of a preceding time window to search for real-time events. Search screen 600 also initially displays a “data summary” dialog as is illustrated in FIG. 6B that enables the user to select different sources for the event data, such as by selecting specific hosts and log files.

After the search is executed, the search screen 600 in FIG. 6A can display the results through search results tabs 604, wherein search results tabs 604 includes: an “events tab” that displays various information about events returned by the search; a “statistics tab” that displays statistics about the search results; and a “visualization tab” that displays various visualizations of the search results. The events tab illustrated in FIG. 6A displays a timeline graph 605 that graphically illustrates the number of events that occurred in one-hour intervals over the selected time range. It also displays an events list 608 that enables a user to view the raw data in each of the returned events. It additionally displays a fields sidebar 606 that includes statistics about occurrences of specific fields in the returned events, including “selected fields” that are pre-selected by the user, and “interesting fields” that are automatically selected by the system based on pre-specified criteria.

2.9. Data Models

A data model is a hierarchically structured search-time mapping of semantic knowledge about one or more datasets. It encodes the domain knowledge necessary to build a variety of specialized searches of those datasets. Those searches, in turn, can be used to generate reports.

A data model is composed of one or more “objects” (or “data model objects”) that define or otherwise correspond to a specific set of data.

Objects in data models can be arranged hierarchically in parent/child relationships. Each child object represents a subset of the dataset covered by its parent object. The top-level objects in data models are collectively referred to as “root objects.”

Child objects have inheritance. Data model objects are defined by characteristics that mostly break down into constraints and attributes. Child objects inherit constraints and attributes from their parent objects and have additional constraints and attributes of their own. Child objects provide a way of filtering events from parent objects. Because a child object always provides an additional constraint in addition to the constraints it has inherited from its parent object, the dataset it represents is always a subset of the dataset that its parent represents.

For example, a first data model object may define a broad set of data pertaining to e-mail activity generally, and another data model object may define specific datasets within the broad dataset, such as a subset of the e-mail data pertaining specifically to e-mails sent. Examples of data models can include electronic mail, authentication, databases, intrusion detection, malware, application state, alerts, compute inventory, network sessions, network traffic, performance, audits, updates, vulnerabilities, etc. Data models and their objects can be designed by knowledge managers in an organization, and they can enable downstream users to quickly focus on a specific set of data. For example, a user can simply select an “e-mail activity” data model object to access a dataset relating to e-mails generally (e.g., sent or received), or select an “e-mails sent” data model object (or data sub-model object) to access a dataset relating to e-mails sent.

A data model object may be defined by (1) a set of search constraints, and (2) a set of fields. Thus, a data model object can be used to quickly search data to identify a set of events and to identify a set of fields to be associated with the set of events. For example, an “e-mails sent” data model object may specify a search for events relating to e-mails that have been sent, and specify a set of fields that are associated with the events. Thus, a user can retrieve and use the “e-mails sent” data model object to quickly search source data for events relating to sent e-mails, and may be provided with a listing of the set of fields relevant to the events in a user interface screen.

A child of the parent data model may be defined by a search (typically a narrower search) that produces a subset of the events that would be produced by the parent data model's search. The child's set of fields can include a subset of the set of fields of the parent data model and/or additional fields. Data model objects that reference the subsets can be arranged in a hierarchical manner, so that child subsets of events are proper subsets of their parents. A user iteratively applies a model development tool (not shown in FIG.) to prepare a query that defines a subset of events and assigns an object name to that subset. A child subset is created by further limiting a query that generated a parent subset. A late-binding schema of field extraction rules is associated with each object or subset in the data model.

Data definitions in associated schemas can be taken from the common information model (CIM) or can be devised for a particular schema and optionally added to the CIM. Child objects inherit fields from parents and can include fields not present in parents. A model developer can select fewer extraction rules than are available for the sources returned by the query that defines events belonging to a model. Selecting a limited set of extraction rules can be a tool for simplifying and focusing the data model, while allowing a user flexibility to explore the data subset. Development of a data model is further explained in U.S. Pat. Nos. 8,788,525 and 8,788,526, both entitled “DATA MODEL FOR MACHINE DATA FOR SEMANTIC SEARCH”, both issued on 22 Jul. 2014, U.S. Pat. No. 8,983,994, entitled “GENERATION OF A DATA MODEL FOR SEARCHING MACHINE DATA”, issued on 17 Mar. 2015, U.S. patent application Ser. No. 14/611,232, entitled “GENERATION OF A DATA MODEL APPLIED TO QUERIES”, filed on 31 Jan. 2015, and U.S. patent application Ser. No. 14/815,884, entitled “GENERATION OF A DATA MODEL APPLIED TO OBJECT QUERIES”, filed on 31 Jul. 2015, each of which is hereby incorporated by reference in its entirety for all purposes. See, also, Knowledge Manager Manual, Build a Data Model, Splunk Enterprise 6.1.3 pp. 150-204 (Aug. 25, 2014).

A data model can also include reports. One or more report formats can be associated with a particular data model and be made available to run against the data model. A user can use child objects to design reports with object datasets that already have extraneous data pre-filtered out. In an embodiment, the data intake and query system 108 provides the user with the ability to produce reports (e.g., a table, chart, visualization, etc.) without having to enter SPL, SQL, or other query language terms into a search screen. Data models are used as the basis for the search feature.

Data models may be selected in a report generation interface. The report generator supports drag-and-drop organization of fields to be summarized in a report. When a model is selected, the fields with available extraction rules are made available for use in the report. The user may refine and/or filter search results to produce more precise reports. The user may select some fields for organizing the report and select other fields for providing detail according to the report organization. For example, “region” and “salesperson” are fields used for organizing the report and sales data can be summarized (subtotaled and totaled) within this organization. The report generator allows the user to specify one or more fields within events and apply statistical analysis on values extracted from the specified one or more fields. The report generator may aggregate search results across sets of events and generate statistics based on aggregated search results. Building reports using the report generation interface is further explained in U.S. patent application Ser. No. 14/503,335, entitled “GENERATING REPORTS FROM UNSTRUCTURED DATA”, filed on 30 Sep. 2014, and which is hereby incorporated by reference in its entirety for all purposes, and in Pivot Manual, Splunk Enterprise 6.1.3 (Aug. 4, 2014). Data visualizations also can be generated in a variety of formats, by reference to the data model. Reports, data visualizations, and data model objects can be saved and associated with the data model for future use. The data model object may be used to perform searches of other data.

FIGS. 12, 13, and 7A-7D illustrate a series of user interface screens where a user may select report generation options using data models. The report generation process may be driven by a predefined data model object, such as a data model object defined and/or saved via a reporting application or a data model object obtained from another source. A user can load a saved data model object using a report editor. For example, the initial search query and fields used to drive the report editor may be obtained from a data model object. The data model object that is used to drive a report generation process may define a search and a set of fields. Upon loading of the data model object, the report generation process may enable a user to use the fields (e.g., the fields defined by the data model object) to define criteria for a report (e.g., filters, split rows/columns, aggregates, etc.) and the search may be used to identify events (e.g., to identify events responsive to the search) used to generate the report. That is, for example, if a data model object is selected to drive a report editor, the graphical user interface of the report editor may enable a user to define reporting criteria for the report using the fields associated with the selected data model object, and the events used to generate the report may be constrained to the events that match, or otherwise satisfy, the search constraints of the selected data model object.

The selection of a data model object for use in driving a report generation may be facilitated by a data model object selection interface. FIG. 12 illustrates an example interactive data model selection graphical user interface 1200 of a report editor that displays a listing of available data models 1201. The user may select one of the data models 1202.

FIG. 13 illustrates an example data model object selection graphical user interface 1300 that displays available data objects 1301 for the selected data object model 1202. The user may select one of the displayed data model objects 1302 for use in driving the report generation process.

Once a data model object is selected by the user, a user interface screen 700 shown in FIG. 7A may display an interactive listing of automatic field identification options 701 based on the selected data model object. For example, a user may select one of the three illustrated options (e.g., the “All Fields” option 702, the “Selected Fields” option 703, or the “Coverage” option (e.g., fields with at least a specified % of coverage) 704). If the user selects the “All Fields” option 702, all of the fields identified from the events that were returned in response to an initial search query may be selected. That is, for example, all of the fields of the identified data model object fields may be selected. If the user selects the “Selected Fields” option 703, only the fields from the fields of the identified data model object fields that are selected by the user may be used. If the user selects the “Coverage” option 704, only the fields of the identified data model object fields meeting a specified coverage criteria may be selected. A percent coverage may refer to the percentage of events returned by the initial search query that a given field appears in. Thus, for example, if an object dataset includes 10,000 events returned in response to an initial search query, and the “avg_age” field appears in 854 of those 10,000 events, then the “avg_age” field would have a coverage of 8.54% for that object dataset. If, for example, the user selects the “Coverage” option and specifies a coverage value of 2%, only fields having a coverage value equal to or greater than 2% may be selected. The number of fields corresponding to each selectable option may be displayed in association with each option. For example, “97” displayed next to the “All Fields” option 702 indicates that 97 fields will be selected if the “All Fields” option is selected. The “3” displayed next to the “Selected Fields” option 703 indicates that 3 of the 97 fields will be selected if the “Selected Fields” option is selected. The “49” displayed next to the “Coverage” option 704 indicates that 49 of the 97 fields (e.g., the 49 fields having a coverage of 2% or greater) will be selected if the “Coverage” option is selected. The number of fields corresponding to the “Coverage” option may be dynamically updated based on the specified percent of coverage.

FIG. 7B illustrates an example graphical user interface screen (also called the pivot interface) 705 displaying the reporting application's “Report Editor” page. The screen may display interactive elements for defining various elements of a report. For example, the page includes a “Filters” element 706, a “Split Rows” element 707, a “Split Columns” element 708, and a “Column Values” element 709. The page may include a list of search results 711. In this example, the Split Rows element 707 is expanded, revealing a listing of fields 710 that can be used to define additional criteria (e.g., reporting criteria). The listing of fields 710 may correspond to the selected fields (attributes). That is, the listing of fields 710 may list only the fields previously selected, either automatically and/or manually by a user. FIG. 7C illustrates a formatting dialogue 712 that may be displayed upon selecting a field from the listing of fields 710. The dialogue can be used to format the display of the results of the selection (e.g., label the column to be displayed as “component”).

FIG. 7D illustrates an example graphical user interface screen 705 including a table of results 713 based on the selected criteria including splitting the rows by the “component” field. A column 714 having an associated count for each component listed in the table may be displayed that indicates an aggregate count of the number of times that the particular field-value pair (e.g., the value in a row) occurs in the set of events responsive to the initial search query.

FIG. 14 illustrates an example graphical user interface screen 1400 that allows the user to filter search results and to perform statistical analysis on values extracted from specific fields in the set of events. In this example, the top ten product names ranked by price are selected as a filter 1401 that causes the display of the ten most popular products sorted by price. Each row is displayed by product name and price 1402. This results in each product displayed in a column labeled “product name” along with an associated price in a column labeled “price” 1406. Statistical analysis of other fields in the events associated with the ten most popular products have been specified as column values 1403. A count of the number of successful purchases for each product is displayed in column 1404. This statistics may be produced by filtering the search results by the product name, finding all occurrences of a successful purchase in a field within the events and generating a total of the number of occurrences. A sum of the total sales is displayed in column 1405, which is a result of the multiplication of the price and the number of successful purchases for each product.

The reporting application allows the user to create graphical visualizations of the statistics generated for a report. For example, FIG. 15 illustrates an example graphical user interface 1500 that displays a set of components and associated statistics 1501. The reporting application allows the user to select a visualization of the statistics in a graph (e.g., bar chart, scatter plot, area chart, line chart, pie chart, radial gauge, marker gauge, filler gauge, etc.). FIG. 16 illustrates an example of a bar chart visualization 1600 of an aspect of the statistical data 1501. FIG. 17 illustrates a scatter plot visualization 1700 of an aspect of the statistical data 1501.

2.10. Acceleration Technique

The above-described system provides significant flexibility by enabling a user to analyze massive quantities of minimally processed data “on the fly” at search time instead of storing pre-specified portions of the data in a database at ingestion time. This flexibility enables a user to see valuable insights, correlate data, and perform subsequent queries to examine interesting aspects of the data that may not have been apparent at ingestion time.

However, performing extraction and analysis operations at search time can involve a large amount of data and require a large number of computational operations, which can cause delays in processing the queries. Advantageously, SPLUNK® ENTERPRISE system employs a number of unique acceleration techniques that have been developed to speed up analysis operations performed at search time. These techniques include: (1) performing search operations in parallel across multiple indexers; (2) using a keyword index; (3) using a high performance analytics store; and (4) accelerating the process of generating reports. These novel techniques are described in more detail below.

2.10.1. Aggregation Technique

To facilitate faster query processing, a query can be structured such that multiple indexers perform the query in parallel, while aggregation of search results from the multiple indexers is performed locally at the search head. For example, FIG. 8 illustrates how a search query 802 received from a client at a search head 210 can split into two phases, including: (1) subtasks 804 (e.g., data retrieval or simple filtering) that may be performed in parallel by indexers 206 for execution, and (2) a search results aggregation operation 806 to be executed by the search head when the results are ultimately collected from the indexers.

During operation, upon receiving search query 802, a search head 210 determines that a portion of the operations involved with the search query may be performed locally by the search head. The search head modifies search query 802 by substituting “stats” (create aggregate statistics over results sets received from the indexers at the search head) with “prestats” (create statistics by the indexer from local results set) to produce search query 804, and then distributes search query 804 to distributed indexers, which are also referred to as “search peers.” Note that search queries may generally specify search criteria or operations to be performed on events that meet the search criteria. Search queries may also specify field names, as well as search criteria for the values in the fields or operations to be performed on the values in the fields. Moreover, the search head may distribute the full search query to the search peers as illustrated in FIG. 4, or may alternatively distribute a modified version (e.g., a more restricted version) of the search query to the search peers. In this example, the indexers are responsible for producing the results and sending them to the search head. After the indexers return the results to the search head, the search head aggregates the received results 806 to form a single search result set. By executing the query in this manner, the system effectively distributes the computational operations across the indexers while minimizing data transfers.

2.10.2. Keyword Index

As described above with reference to the flow charts in FIG. 3 and FIG. 4, data intake and query system 108 can construct and maintain one or more keyword indices to quickly identify events containing specific keywords. This technique can greatly speed up the processing of queries involving specific keywords. As mentioned above, to build a keyword index, an indexer first identifies a set of keywords. Then, the indexer includes the identified keywords in an index, which associates each stored keyword with references to events containing that keyword, or to locations within events where that keyword is located. When an indexer subsequently receives a keyword-based query, the indexer can access the keyword index to quickly identify events containing the keyword.

2.10.3. High Performance Analytics Store

To speed up certain types of queries, some embodiments of system 108 create a high performance analytics store, which is referred to as a “summarization table,” that contains entries for specific field-value pairs. Each of these entries keeps track of instances of a specific value in a specific field in the event data and includes references to events containing the specific value in the specific field. For example, an example entry in a summarization table can keep track of occurrences of the value “94107” in a “ZIP code” field of a set of events and the entry includes references to all of the events that contain the value “94107” in the ZIP code field. This optimization technique enables the system to quickly process queries that seek to determine how many events have a particular value for a particular field. To this end, the system can examine the entry in the summarization table to count instances of the specific value in the field without having to go through the individual events or perform data extractions at search time. Also, if the system needs to process all events that have a specific field-value combination, the system can use the references in the summarization table entry to directly access the events to extract further information without having to search all of the events to find the specific field-value combination at search time.

In some embodiments, the system maintains a separate summarization table for each of the above-described time-specific buckets that stores events for a specific time range. A bucket-specific summarization table includes entries for specific field-value combinations that occur in events in the specific bucket. Alternatively, the system can maintain a separate summarization table for each indexer. The indexer-specific summarization table includes entries for the events in a data store that are managed by the specific indexer. Indexer-specific summarization tables may also be bucket-specific.

The summarization table can be populated by running a periodic query that scans a set of events to find instances of a specific field-value combination, or alternatively instances of all field-value combinations for a specific field. A periodic query can be initiated by a user, or can be scheduled to occur automatically at specific time intervals. A periodic query can also be automatically launched in response to a query that asks for a specific field-value combination.

In some cases, when the summarization tables may not cover all of the events that are relevant to a query, the system can use the summarization tables to obtain partial results for the events that are covered by summarization tables, but may also have to search through other events that are not covered by the summarization tables to produce additional results. These additional results can then be combined with the partial results to produce a final set of results for the query. The summarization table and associated techniques are described in more detail in U.S. Pat. No. 8,682,925, entitled “Distributed High Performance Analytics Store”, issued on 25 Mar. 2014, U.S. patent application Ser. No. 14/170,159, entitled “SUPPLEMENTING A HIGH PERFORMANCE ANALYTICS STORE WITH EVALUATION OF INDIVIDUAL EVENTS TO RESPOND TO AN EVENT QUERY”, filed on 31 Jan. 2014, and U.S. patent application Ser. No. 14/815,973, entitled “STORAGE MEDIUM AND CONTROL DEVICE”, filed on 21 Feb. 2014, each of which is hereby incorporated by reference in its entirety.

2.10.4. Accelerating Report Generation

In some embodiments, a data server system such as the SPLUNK® ENTERPRISE system can accelerate the process of periodically generating updated reports based on query results. To accelerate this process, a summarization engine automatically examines the query to determine whether generation of updated reports can be accelerated by creating intermediate summaries. If reports can be accelerated, the summarization engine periodically generates a summary covering data obtained during a latest non-overlapping time period. For example, where the query seeks events meeting a specified criteria, a summary for the time period includes only events within the time period that meet the specified criteria. Similarly, if the query seeks statistics calculated from the events, such as the number of events that match the specified criteria, then the summary for the time period includes the number of events in the period that match the specified criteria.

In addition to the creation of the summaries, the summarization engine schedules the periodic updating of the report associated with the query. During each scheduled report update, the query engine determines whether intermediate summaries have been generated covering portions of the time period covered by the report update. If so, then the report is generated based on the information contained in the summaries. Also, if additional event data has been received and has not yet been summarized, and is required to generate the complete report, the query can be run on this additional event data. Then, the results returned by this query on the additional event data, along with the partial results obtained from the intermediate summaries, can be combined to generate the updated report. This process is repeated each time the report is updated. Alternatively, if the system stores events in buckets covering specific time ranges, then the summaries can be generated on a bucket-by-bucket basis. Note that producing intermediate summaries can save the work involved in re-running the query for previous time periods, so advantageously only the newer event data needs to be processed while generating an updated report. These report acceleration techniques are described in more detail in U.S. Pat. No. 8,589,403, entitled “Compressed Journaling In Event Tracking Files For Metadata Recovery And Replication”, issued on 19 Nov. 2013, U.S. Pat. No. 8,412,696, entitled “Real Time Searching And Reporting”, issued on 2 Apr. 2011, and U.S. Pat. Nos. 8,589,375 and 8,589,432, both also entitled “REAL TIME SEARCHING AND REPORTING”, both issued on 19 Nov. 2013, each of which is hereby incorporated by reference in its entirety.

2.11. Security Features

The SPLUNK® ENTERPRISE platform provides various schemas, dashboards and visualizations that simplify developers' task to create applications with additional capabilities. One such application is the SPLUNK® APP FOR ENTERPRISE SECURITY, which performs monitoring and alerting operations and includes analytics to facilitate identifying both known and unknown security threats based on large volumes of data stored by the SPLUNK® ENTERPRISE system. SPLUNK® APP FOR ENTERPRISE SECURITY provides the security practitioner with visibility into security-relevant threats found in the enterprise infrastructure by capturing, monitoring, and reporting on data from enterprise security devices, systems, and applications. Through the use of SPLUNK® ENTERPRISE searching and reporting capabilities, SPLUNK® APP FOR ENTERPRISE SECURITY provides a top-down and bottom-up view of an organization's security posture.

The SPLUNK® APP FOR ENTERPRISE SECURITY leverages SPLUNK® ENTERPRISE search-time normalization techniques, saved searches, and correlation searches to provide visibility into security-relevant threats and activity and generate notable events for tracking. The App enables the security practitioner to investigate and explore the data to find new or unknown threats that do not follow signature-based patterns.

Conventional Security Information and Event Management (SIEM) systems that lack the infrastructure to effectively store and analyze large volumes of security-related data. Traditional SIEM systems typically use fixed schemas to extract data from pre-defined security-related fields at data ingestion time and storing the extracted data in a relational database. This traditional data extraction process (and associated reduction in data size) that occurs at data ingestion time inevitably hampers future incident investigations that may need original data to determine the root cause of a security issue, or to detect the onset of an impending security threat.

In contrast, the SPLUNK® APP FOR ENTERPRISE SECURITY system stores large volumes of minimally processed security-related data at ingestion time for later retrieval and analysis at search time when a live security threat is being investigated. To facilitate this data retrieval process, the SPLUNK® APP FOR ENTERPRISE SECURITY provides pre-specified schemas for extracting relevant values from the different types of security-related event data and enables a user to define such schemas.

The SPLUNK® APP FOR ENTERPRISE SECURITY can process many types of security-related information. In general, this security-related information can include any information that can be used to identify security threats. For example, the security-related information can include network-related information, such as IP addresses, domain names, asset identifiers, network traffic volume, uniform resource locator strings, and source addresses. The process of detecting security threats for network-related information is further described in U.S. Pat. No. 8,826,434, entitled “SECURITY THREAT DETECTION BASED ON INDICATIONS IN BIG DATA OF ACCESS TO NEWLY REGISTERED DOMAINS”, issued on 2 Sep. 2014, U.S. patent application Ser. No. 13/956,252, entitled “INVESTIGATIVE AND DYNAMIC DETECTION OF POTENTIAL SECURITY-THREAT INDICATORS FROM EVENTS IN BIG DATA”, filed on 31 Jul. 2013, U.S. patent application Ser. No. 14/445,018, entitled “GRAPHIC DISPLAY OF SECURITY THREATS BASED ON INDICATIONS OF ACCESS TO NEWLY REGISTERED DOMAINS”, filed on 28 Jul. 2014, U.S. patent application Ser. No. 14/445,023, entitled “SECURITY THREAT DETECTION OF NEWLY REGISTERED DOMAINS”, filed on 28 Jul. 2014, U.S. patent application Ser. No. 14/815,971, entitled “SECURITY THREAT DETECTION USING DOMAIN NAME ACCESSES”, filed on 1 Aug. 2015, and U.S. patent application Ser. No. 14/815,972, entitled “SECURITY THREAT DETECTION USING DOMAIN NAME REGISTRATIONS”, filed on 1 Aug. 2015, each of which is hereby incorporated by reference in its entirety for all purposes. Security-related information can also include malware infection data and system configuration information, as well as access control information, such as login/logout information and access failure notifications. The security-related information can originate from various sources within a data center, such as hosts, virtual machines, storage devices and sensors. The security-related information can also originate from various sources in a network, such as routers, switches, email servers, proxy servers, gateways, firewalls and intrusion-detection systems.

During operation, the SPLUNK® APP FOR ENTERPRISE SECURITY facilitates detecting “notable events” that are likely to indicate a security threat. These notable events can be detected in a number of ways: (1) a user can notice a correlation in the data and can manually identify a corresponding group of one or more events as “notable;” or (2) a user can define a “correlation search” specifying criteria for a notable event, and every time one or more events satisfy the criteria, the application can indicate that the one or more events are notable. A user can alternatively select a pre-defined correlation search provided by the application. Note that correlation searches can be run continuously or at regular intervals (e.g., every hour) to search for notable events. Upon detection, notable events can be stored in a dedicated “notable events index,” which can be subsequently accessed to generate various visualizations containing security-related information. Also, alerts can be generated to notify system operators when important notable events are discovered.

The SPLUNK® APP FOR ENTERPRISE SECURITY provides various visualizations to aid in discovering security threats, such as a “key indicators view” that enables a user to view security metrics, such as counts of different types of notable events. For example, FIG. 9A illustrates an example key indicators view 900 that comprises a dashboard, which can display a value 901, for various security-related metrics, such as malware infections 902. It can also display a change in a metric value 903, which indicates that the number of malware infections increased by 63 during the preceding interval. Key indicators view 900 additionally displays a histogram panel 904 that displays a histogram of notable events organized by urgency values, and a histogram of notable events organized by time intervals. This key indicators view is described in further detail in pending U.S. patent application Ser. No. 13/956,338, entitled “Key Indicators View”, filed on 31 Jul. 2013, and which is hereby incorporated by reference in its entirety for all purposes.

These visualizations can also include an “incident review dashboard” that enables a user to view and act on “notable events.” These notable events can include: (1) a single event of high importance, such as any activity from a known web attacker; or (2) multiple events that collectively warrant review, such as a large number of authentication failures on a host followed by a successful authentication. For example, FIG. 9B illustrates an example incident review dashboard 910 that includes a set of incident attribute fields 911 that, for example, enables a user to specify a time range field 912 for the displayed events. It also includes a timeline 913 that graphically illustrates the number of incidents that occurred in time intervals over the selected time range. It additionally displays an events list 914 that enables a user to view a list of all of the notable events that match the criteria in the incident attributes fields 911. To facilitate identifying patterns among the notable events, each notable event can be associated with an urgency value (e.g., low, medium, high, critical), which is indicated in the incident review dashboard. The urgency value for a detected event can be determined based on the severity of the event and the priority of the system component associated with the event.

2.12. Data Center Monitoring

As mentioned above, the SPLUNK® ENTERPRISE platform provides various features that simplify the developers's task to create various applications. One such application is SPLUNK® APP FOR VMWARE® that provides operational visibility into granular performance metrics, logs, tasks and events, and topology from hosts, virtual machines and virtual centers. It empowers administrators with an accurate real-time picture of the health of the environment, proactively identifying performance and capacity bottlenecks.

Conventional data-center-monitoring systems lack the infrastructure to effectively store and analyze large volumes of machine-generated data, such as performance information and log data obtained from the data center. In conventional data-center-monitoring systems, machine-generated data is typically pre-processed prior to being stored, for example, by extracting pre-specified data items and storing them in a database to facilitate subsequent retrieval and analysis at search time. However, the rest of the data is not saved and discarded during pre-processing.

In contrast, the SPLUNK® APP FOR VMWARE® stores large volumes of minimally processed machine data, such as performance information and log data, at ingestion time for later retrieval and analysis at search time when a live performance issue is being investigated. In addition to data obtained from various log files, this performance-related information can include values for performance metrics obtained through an application programming interface (API) provided as part of the vSphere Hypervisor™ system distributed by VMware, Inc. of Palo Alto, Calif. For example, these performance metrics can include: (1) CPU-related performance metrics; (2) disk-related performance metrics; (3) memory-related performance metrics; (4) network-related performance metrics; (5) energy-usage statistics; (6) data-traffic-related performance metrics; (7) overall system availability performance metrics; (8) cluster-related performance metrics; and (9) virtual machine performance statistics. Such performance metrics are described in U.S. patent application Ser. No. 14/167,316, entitled “Correlation For User-Selected Time Ranges Of Values For Performance Metrics Of Components In An Information-Technology Environment With Log Data From That Information-Technology Environment”, filed on 29 Jan. 2014, and which is hereby incorporated by reference in its entirety for all purposes.

To facilitate retrieving information of interest from performance data and log files, the SPLUNK® APP FOR VMWARE® provides pre-specified schemas for extracting relevant values from different types of performance-related event data, and also enables a user to define such schemas.

The SPLUNK® APP FOR VMWARE® additionally provides various visualizations to facilitate detecting and diagnosing the root cause of performance problems. For example, one such visualization is a “proactive monitoring tree” that enables a user to easily view and understand relationships among various factors that affect the performance of a hierarchically structured computing system. This proactive monitoring tree enables a user to easily navigate the hierarchy by selectively expanding nodes representing various entities (e.g., virtual centers or computing clusters) to view performance information for lower-level nodes associated with lower-level entities (e.g., virtual machines or host systems). Example node-expansion operations are illustrated in FIG. 9C, wherein nodes 933 and 934 are selectively expanded. Note that nodes 931-939 can be displayed using different patterns or colors to represent different performance states, such as a critical state, a warning state, a normal state or an unknown/offline state. The ease of navigation provided by selective expansion in combination with the associated performance-state information enables a user to quickly diagnose the root cause of a performance problem. The proactive monitoring tree is described in further detail in U.S. patent application Ser. No. 14/253,490, entitled “PROACTIVE MONITORING TREE WITH SEVERITY STATE SORTING”, filed on 15 Apr. 2014, and U.S. patent application Ser. No. 14/812,948, also entitled “PROACTIVE MONITORING TREE WITH SEVERITY STATE SORTING”, filed on 29 Jul. 2015, each of which is hereby incorporated by reference in its entirety for all purposes.

The SPLUNK® APP FOR VMWARE® also provides a user interface that enables a user to select a specific time range and then view heterogeneous data comprising events, log data, and associated performance metrics for the selected time range. For example, the screen illustrated in FIG. 9D displays a listing of recent “tasks and events” and a listing of recent “log entries” for a selected time range above a performance-metric graph for “average CPU core utilization” for the selected time range. Note that a user is able to operate pull-down menus 942 to selectively display different performance metric graphs for the selected time range. This enables the user to correlate trends in the performance-metric graph with corresponding event and log data to quickly determine the root cause of a performance problem. This user interface is described in more detail in U.S. patent application Ser. No. 14/167,316, entitled “Correlation For User-Selected Time Ranges Of Values For Performance Metrics Of Components In An Information-Technology Environment With Log Data From That Information-Technology ENVIRONMENT”, filed on 29 Jan. 2014, and which is hereby incorporated by reference in its entirety for all purposes.

2.13. Cloud-Based System Overview

The example data intake and query system 108 described in reference to FIG. 2 comprises several system components, including one or more forwarders, indexers, and search heads. In some environments, a user of a data intake and query system 108 may install and configure, on computing devices owned and operated by the user, one or more software applications that implement some or all of these system components. For example, a user may install a software application on server computers owned by the user and configure each server to operate as one or more of a forwarder, an indexer, a search head, etc. This arrangement generally may be referred to as an “on-premises” solution. That is, the system 108 is installed and operates on computing devices directly controlled by the user of the system. Some users may prefer an on-premises solution because it may provide a greater level of control over the configuration of certain aspects of the system (e.g., security, privacy, standards, controls, etc.). However, other users may instead prefer an arrangement in which the user is not directly responsible for providing and managing the computing devices upon which various components of system 108 operate.

In one embodiment, to provide an alternative to an entirely on-premises environment for system 108, one or more of the components of a data intake and query system instead may be provided as a cloud-based service. In this context, a cloud-based service refers to a service hosted by one more computing resources that are accessible to end users over a network, for example, by using a web browser or other application on a client device to interface with the remote computing resources. For example, a service provider may provide a cloud-based data intake and query system by managing computing resources configured to implement various aspects of the system (e.g., forwarders, indexers, search heads, etc.) and by providing access to the system to end users via a network. Typically, a user may pay a subscription or other fee to use such a service. Each subscribing user of the cloud-based service may be provided with an account that enables the user to configure a customized cloud-based system based on the user's preferences.

FIG. 10 illustrates a block diagram of an example cloud-based data intake and query system. Similar to the system of FIG. 2, the networked computer system 1000 includes input data sources 202 and forwarders 204. These input data sources and forwarders may be in a subscriber's private computing environment. Alternatively, they might be directly managed by the service provider as part of the cloud service. In the example system 1000, one or more forwarders 204 and client devices 1002 are coupled to a cloud-based data intake and query system 1006 via one or more networks 1004. Network 1004 broadly represents one or more LANs, WANs, cellular networks, intranetworks, internetworks, etc., using any of wired, wireless, terrestrial microwave, satellite links, etc., and may include the public Internet, and is used by client devices 1002 and forwarders 204 to access the system 1006. Similar to the system of 108, each of the forwarders 204 may be configured to receive data from an input source and to forward the data to other components of the system 1006 for further processing.

In an embodiment, a cloud-based data intake and query system 1006 may comprise a plurality of system instances 1008. In general, each system instance 1008 may include one or more computing resources managed by a provider of the cloud-based system 1006 made available to a particular subscriber. The computing resources comprising a system instance 1008 may, for example, include one or more servers or other devices configured to implement one or more forwarders, indexers, search heads, and other components of a data intake and query system, similar to system 108. As indicated above, a subscriber may use a web browser or other application of a client device 1002 to access a web portal or other interface that enables the subscriber to configure an instance 1008.

Providing a data intake and query system as described in reference to system 108 as a cloud-based service presents a number of challenges. Each of the components of a system 108 (e.g., forwarders, indexers and search heads) may at times refer to various configuration files stored locally at each component. These configuration files typically may involve some level of user configuration to accommodate particular types of data a user desires to analyze and to account for other user preferences. However, in a cloud-based service context, users typically may not have direct access to the underlying computing resources implementing the various system components (e.g., the computing resources comprising each system instance 1008) and may desire to make such configurations indirectly, for example, using one or more web-based interfaces. Thus, the techniques and systems described herein for providing user interfaces that enable a user to configure source type definitions are applicable to both on-premises and cloud-based service contexts, or some combination thereof (e.g., a hybrid system where both an on-premises environment such as SPLUNK® ENTERPRISE and a cloud-based environment such as SPLUNK CLOUD™ are centrally visible).

2.14. Searching Externally Archived Data

FIG. 11 shows a block diagram of an example of a data intake and query system 108 that provides transparent search facilities for data systems that are external to the data intake and query system. Such facilities are available in the HUNK® system provided by Splunk Inc. of San Francisco, Calif. HUNK® represents an analytics platform that enables business and IT teams to rapidly explore, analyze, and visualize data in Hadoop and NoSQL data stores.

The search head 210 of the data intake and query system receives search requests from one or more client devices 1104 over network connections 1120. As discussed above, the data intake and query system 108 may reside in an enterprise location, in the cloud, etc. FIG. 11 illustrates that multiple client devices 1104 a, 1104 b, . . . , 1104 n may communicate with the data intake and query system 108. The client devices 1104 may communicate with the data intake and query system using a variety of connections. For example, one client device in FIG. 11 is illustrated as communicating over an Internet (Web) protocol, another client device is illustrated as communicating via a command line interface, and another client device is illustrated as communicating via a system developer kit (SDK).

The search head 210 analyzes the received search request to identify request parameters. If a search request received from one of the client devices 1104 references an index maintained by the data intake and query system, then the search head 210 connects to one or more indexers 206 of the data intake and query system for the index referenced in the request parameters. That is, if the request parameters of the search request reference an index, then the search head accesses the data in the index via the indexer. The data intake and query system 108 may include one or more indexers 206, depending on system access resources and requirements. As described further below, the indexers 206 retrieve data from their respective local data stores 208 as specified in the search request. The indexers and their respective data stores can comprise one or more storage devices and typically reside on the same system, though they may be connected via a local network connection.

If the request parameters of the received search request reference an external data collection, which is not accessible to the indexers 206 or under the management of the data intake and query system, then the search head 210 can access the external data collection through an External Result Provider (ERP) process 1110. An external data collection may be referred to as a “virtual index” (plural, “virtual indices”). An ERP process provides an interface through which the search head 210 may access virtual indices.

Thus, a search reference to an index of the system relates to a locally stored and managed data collection. In contrast, a search reference to a virtual index relates to an externally stored and managed data collection, which the search head may access through one or more ERP processes 1110, 1112. FIG. 11 shows two ERP processes 1110, 1112 that connect to respective remote (external) virtual indices, which are indicated as a Hadoop or another system 1114 (e.g., Amazon S3, Amazon EMR, other Hadoop Compatible File Systems (HCFS), etc.) and a relational database management system (RDBMS) 1116. Other virtual indices may include other file organizations and protocols, such as Structured Query Language (SQL) and the like. The ellipses between the ERP processes 1110, 1112 indicate optional additional ERP processes of the data intake and query system 108. An ERP process may be a computer process that is initiated or spawned by the search head 210 and is executed by the search data intake and query system 108. Alternatively or additionally, an ERP process may be a process spawned by the search head 210 on the same or different host system as the search head 210 resides.

The search head 210 may spawn a single ERP process in response to multiple virtual indices referenced in a search request, or the search head may spawn different ERP processes for different virtual indices. Generally, virtual indices that share common data configurations or protocols may share ERP processes. For example, all search query references to a Hadoop file system may be processed by the same ERP process, if the ERP process is suitably configured. Likewise, all search query references to an SQL database may be processed by the same ERP process. In addition, the search head may provide a common ERP process for common external data source types (e.g., a common vendor may utilize a common ERP process, even if the vendor includes different data storage system types, such as Hadoop and SQL). Common indexing schemes also may be handled by common ERP processes, such as flat text files or Weblog files.

The search head 210 determines the number of ERP processes to be initiated via the use of configuration parameters that are included in a search request message. Generally, there is a one-to-many relationship between an external results provider “family” and ERP processes. There is also a one-to-many relationship between an ERP process and corresponding virtual indices that are referred to in a search request. For example, using RDBMS, assume two independent instances of such a system by one vendor, such as one RDBMS for production and another RDBMS used for development. In such a situation, it is likely preferable (but optional) to use two ERP processes to maintain the independent operation as between production and development data. Both of the ERPs, however, will belong to the same family, because the two RDBMS system types are from the same vendor.

The ERP processes 1110, 1112 receive a search request from the search head 210. The search head may optimize the received search request for execution at the respective external virtual index. Alternatively, the ERP process may receive a search request as a result of analysis performed by the search head or by a different system process. The ERP processes 1110, 1112 can communicate with the search head 210 via conventional input/output routines (e.g., standard in/standard out, etc.). In this way, the ERP process receives the search request from a client device such that the search request may be efficiently executed at the corresponding external virtual index.

The ERP processes 1110, 1112 may be implemented as a process of the data intake and query system. Each ERP process may be provided by the data intake and query system, or may be provided by process or application providers who are independent of the data intake and query system. Each respective ERP process may include an interface application installed at a computer of the external result provider that ensures proper communication between the search support system and the external result provider. The ERP processes 1110, 1112 generate appropriate search requests in the protocol and syntax of the respective virtual indices 1114, 1116, each of which corresponds to the search request received by the search head 210. Upon receiving search results from their corresponding virtual indices, the respective ERP process passes the result to the search head 210, which may return or display the results or a processed set of results based on the returned results to the respective client device.

Client devices 1104 may communicate with the data intake and query system 108 through a network interface 1120, e.g., one or more LANs, WANs, cellular networks, intranetworks, and/or internetworks using any of wired, wireless, terrestrial microwave, satellite links, etc., and may include the public Internet.

The analytics platform utilizing the External Result Provider process described in more detail in U.S. Pat. No. 8,738,629, entitled “External Result Provided Process For Retrieving Data Stored Using A Different Configuration Or Protocol”, issued on 27 May 2014, U.S. Pat. No. 8,738,587, entitled “PROCESSING A SYSTEM SEARCH REQUEST BY RETRIEVING RESULTS FROM BOTH A NATIVE INDEX AND A VIRTUAL INDEX”, issued on 25 Jul. 2013, U.S. patent application Ser. No. 14/266,832, entitled “PROCESSING A SYSTEM SEARCH REQUEST ACROSS DISPARATE DATA COLLECTION SYSTEMS”, filed on 1 May 2014, and U.S. patent application Ser. No. 14/449,144, entitled “PROCESSING A SYSTEM SEARCH REQUEST INCLUDING EXTERNAL DATA SOURCES”, filed on 31 Jul. 2014, each of which is hereby incorporated by reference in its entirety for all purposes.

2.14.1. ERP Process Features

The ERP processes described above may include two operation modes: a streaming mode and a reporting mode. The ERP processes can operate in streaming mode only, in reporting mode only, or in both modes simultaneously. Operating in both modes simultaneously is referred to as mixed mode operation. In a mixed mode operation, the ERP at some point can stop providing the search head with streaming results and only provide reporting results thereafter, or the search head at some point may start ignoring streaming results it has been using and only use reporting results thereafter.

The streaming mode returns search results in real time, with minimal processing, in response to the search request. The reporting mode provides results of a search request with processing of the search results prior to providing them to the requesting search head, which in turn provides results to the requesting client device. ERP operation with such multiple modes provides greater performance flexibility with regard to report time, search latency, and resource utilization.

In a mixed mode operation, both streaming mode and reporting mode are operating simultaneously. The streaming mode results (e.g., the raw data obtained from the external data source) are provided to the search head, which can then process the results data (e.g., break the raw data into events, timestamp it, filter it, etc.) and integrate the results data with the results data from other external data sources, and/or from data stores of the search head. The search head performs such processing and can immediately start returning interim (streaming mode) results to the user at the requesting client device; simultaneously, the search head is waiting for the ERP process to process the data it is retrieving from the external data source as a result of the concurrently executing reporting mode.

In some instances, the ERP process initially operates in a mixed mode, such that the streaming mode operates to enable the ERP quickly to return interim results (e.g., some of the raw or unprocessed data necessary to respond to a search request) to the search head, enabling the search head to process the interim results and begin providing to the client or search requester interim results that are responsive to the query. Meanwhile, in this mixed mode, the ERP also operates concurrently in reporting mode, processing portions of raw data in a manner responsive to the search query. Upon determining that it has results from the reporting mode available to return to the search head, the ERP may halt processing in the mixed mode at that time (or some later time) by stopping the return of data in streaming mode to the search head and switching to reporting mode only. The ERP at this point starts sending interim results in reporting mode to the search head, which in turn may then present this processed data responsive to the search request to the client or search requester. Typically the search head switches from using results from the ERP's streaming mode of operation to results from the ERP's reporting mode of operation when the higher bandwidth results from the reporting mode outstrip the amount of data processed by the search head in the streaming mode of ERP operation.

A reporting mode may have a higher bandwidth because the ERP does not have to spend time transferring data to the search head for processing all the raw data. In addition, the ERP may optionally direct another processor to do the processing.

The streaming mode of operation does not need to be stopped to gain the higher bandwidth benefits of a reporting mode; the search head could simply stop using the streaming mode results—and start using the reporting mode results—when the bandwidth of the reporting mode has caught up with or exceeded the amount of bandwidth provided by the streaming mode. Thus, a variety of triggers and ways to accomplish a search head's switch from using streaming mode results to using reporting mode results may be appreciated by one skilled in the art.

The reporting mode can involve the ERP process (or an external system) performing event breaking, time stamping, filtering of events to match the search query request, and calculating statistics on the results. The user can request particular types of data, such as if the search query itself involves types of events, or the search request may ask for statistics on data, such as on events that meet the search request. In either case, the search head understands the query language used in the received query request, which may be a proprietary language. One exemplary query language is Splunk Processing Language (SPL) developed by the assignee of the application, Splunk Inc. The search head typically understands how to use that language to obtain data from the indexers, which store data in a format used by the SPLUNK® Enterprise system.

The ERP processes support the search head, as the search head is not ordinarily configured to understand the format in which data is stored in external data sources such as Hadoop or SQL data systems. Rather, the ERP process performs that translation from the query submitted in the search support system's native format (e.g., SPL if SPLUNK® ENTERPRISE is used as the search support system) to a search query request format that will be accepted by the corresponding external data system. The external data system typically stores data in a different format from that of the search support system's native index format, and it utilizes a different query language (e.g., SQL or MapReduce, rather than SPL or the like).

As noted, the ERP process can operate in the streaming mode alone. After the ERP process has performed the translation of the query request and received raw results from the streaming mode, the search head can integrate the returned data with any data obtained from local data sources (e.g., native to the search support system), other external data sources, and other ERP processes (if such operations were required to satisfy the terms of the search query). An advantage of mixed mode operation is that, in addition to streaming mode, the ERP process is also executing concurrently in reporting mode. Thus, the ERP process (rather than the search head) is processing query results (e.g., performing event breaking, timestamping, filtering, possibly calculating statistics if required to be responsive to the search query request, etc.). It should be apparent to those skilled in the art that additional time is needed for the ERP process to perform the processing in such a configuration. Therefore, the streaming mode will allow the search head to start returning interim results to the user at the client device before the ERP process can complete sufficient processing to start returning any search results. The switchover between streaming and reporting mode happens when the ERP process determines that the switchover is appropriate, such as when the ERP process determines it can begin returning meaningful results from its reporting mode.

The operation described above illustrates the source of operational latency: streaming mode has low latency (immediate results) and usually has relatively low bandwidth (fewer results can be returned per unit of time). In contrast, the concurrently running reporting mode has relatively high latency (it has to perform a lot more processing before returning any results) and usually has relatively high bandwidth (more results can be processed per unit of time). For example, when the ERP process does begin returning report results, it returns more processed results than in the streaming mode, because, e.g., statistics only need to be calculated to be responsive to the search request. That is, the ERP process doesn't have to take time to first return raw data to the search head. As noted, the ERP process could be configured to operate in streaming mode alone and return just the raw data for the search head to process in a way that is responsive to the search request. Alternatively, the ERP process can be configured to operate in the reporting mode only. Also, the ERP process can be configured to operate in streaming mode and reporting mode concurrently, as described, with the ERP process stopping the transmission of streaming results to the search head when the concurrently running reporting mode has caught up and started providing results. The reporting mode does not require the processing of all raw data that is responsive to the search query request before the ERP process starts returning results; rather, the reporting mode usually performs processing of chunks of events and returns the processing results to the search head for each chunk.

For example, an ERP process can be configured to merely return the contents of a search result file verbatim, with little or no processing of results. That way, the search head performs all processing (such as parsing byte streams into events, filtering, etc.). The ERP process can be configured to perform additional intelligence, such as analyzing the search request and handling all the computation that a native search indexer process would otherwise perform. In this way, the configured ERP process provides greater flexibility in features while operating according to desired preferences, such as response latency and resource requirements.

2.15. IT Service Monitoring

As previously mentioned, the SPLUNK® ENTERPRISE platform provides various schemas, dashboards and visualizations that make it easy for developers to create applications to provide additional capabilities. One such application is SPLUNK® IT SERVICE INTELLIGENCE™, which performs monitoring and alerting operations. It also includes analytics to help an analyst diagnose the root cause of performance problems based on large volumes of data stored by the SPLUNK® ENTERPRISE system as correlated to the various services an IT organization provides (a service-centric view). This differs significantly from conventional IT monitoring systems that lack the infrastructure to effectively store and analyze large volumes of service-related event data. Traditional service monitoring systems typically use fixed schemas to extract data from pre-defined fields at data ingestion time, wherein the extracted data is typically stored in a relational database. This data extraction process and associated reduction in data content that occurs at data ingestion time inevitably hampers future investigations, when all of the original data may be needed to determine the root cause of or contributing factors to a service issue.

In contrast, a SPLUNK® IT SERVICE INTELLIGENCE™ system stores large volumes of minimally-processed service-related data at ingestion time for later retrieval and analysis at search time, to perform regular monitoring, or to investigate a service issue. To facilitate this data retrieval process, SPLUNK® IT SERVICE INTELLIGENCE™ enables a user to define an IT operations infrastructure from the perspective of the services it provides. In this service-centric approach, a service such as corporate e-mail may be defined in terms of the entities employed to provide the service, such as host machines and network devices. Each entity is defined to include information for identifying all of the event data that pertains to the entity, whether produced by the entity itself or by another machine, and considering the many various ways the entity may be identified in raw machine data (such as by a URL, an IP address, or machine name). The service and entity definitions can organize event data around a service so that all of the event data pertaining to that service can be easily identified. This capability provides a foundation for the implementation of Key Performance Indicators.

One or more Key Performance Indicators (KPI's) are defined for a service within the SPLUNK® IT SERVICE INTELLIGENCE™ application. Each KPI measures an aspect of service performance at a point in time or over a period of time (aspect KPI's). Each KPI is defined by a search query that derives a KPI value from the machine data of events associated with the entities that provide the service. Information in the entity definitions may be used to identify the appropriate events at the time a KPI is defined or whenever a KPI value is being determined. The KPI values derived over time may be stored to build a valuable repository of current and historical performance information for the service, and the repository, itself, may be subject to search query processing. Aggregate KPIs may be defined to provide a measure of service performance calculated from a set of service aspect KPI values; this aggregate may even be taken across defined timeframes and/or across multiple services. A particular service may have an aggregate KPI derived from substantially all of the aspect KPI's of the service to indicate an overall health score for the service.

SPLUNK® IT SERVICE INTELLIGENCE™ facilitates the production of meaningful aggregate KPI's through a system of KPI thresholds and state values. Different KPI definitions may produce values in different ranges, and so the same value may mean something very different from one KPI definition to another. To address this, SPLUNK® IT SERVICE INTELLIGENCE™ implements a translation of individual KPI values to a common domain of “state” values. For example, a KPI range of values may be 1-100, or 50-275, while values in the state domain may be ‘critical,’ ‘warning,’‘normal,’ and ‘informational’. Thresholds associated with a particular KPI definition determine ranges of values for that KPI that correspond to the various state values. In one case, KPI values 95-100 may be set to correspond to ‘critical’ in the state domain. KPI values from disparate KPI's can be processed uniformly once they are translated into the common state values using the thresholds. For example, “normal 80% of the time” can be applied across various KPI's. To provide meaningful aggregate KPI's, a weighting value can be assigned to each KPI so that its influence on the calculated aggregate KPI value is increased or decreased relative to the other KPI's.

One service in an IT environment often impacts, or is impacted by, another service. SPLUNK® IT SERVICE INTELLIGENCE™ can reflect these dependencies. For example, a dependency relationship between a corporate e-mail service and a centralized authentication service can be reflected by recording an association between their respective service definitions. The recorded associations establish a service dependency topology that informs the data or selection options presented in a GUI, for example. (The service dependency topology is like a “map” showing how services are connected based on their dependencies.) The service topology may itself be depicted in a GUI and may be interactive to allow navigation among related services.

Entity definitions in SPLUNK® IT SERVICE INTELLIGENCE™ can include informational fields that can serve as metadata, implied data fields, or attributed data fields for the events identified by other aspects of the entity definition. Entity definitions in SPLUNK® IT SERVICE INTELLIGENCE™ can also be created and updated by an import of tabular data (as represented in a CSV, another delimited file, or a search query result set). The import may be GUI-mediated or processed using import parameters from a GUI-based import definition process. Entity definitions in SPLUNK® IT SERVICE INTELLIGENCE™ can also be associated with a service by means of a service definition rule. Processing the rule results in the matching entity definitions being associated with the service definition. The rule can be processed at creation time, and thereafter on a scheduled or on-demand basis. This allows dynamic, rule-based updates to the service definition.

During operation, SPLUNK® IT SERVICE INTELLIGENCE™ can recognize so-called “notable events” that may indicate a service performance problem or other situation of interest. These notable events can be recognized by a “correlation search” specifying trigger criteria for a notable event: every time KPI values satisfy the criteria, the application indicates a notable event. A severity level for the notable event may also be specified. Furthermore, when trigger criteria are satisfied, the correlation search may additionally or alternatively cause a service ticket to be created in an IT service management (ITSM) system, such as a systems available from ServiceNow, Inc., of Santa Clara, Calif.

SPLUNK® IT SERVICE INTELLIGENCE™ provides various visualizations built on its service-centric organization of event data and the KPI values generated and collected. Visualizations can be particularly useful for monitoring or investigating service performance. SPLUNK® IT SERVICE INTELLIGENCE™ provides a service monitoring interface suitable as the home page for ongoing IT service monitoring. The interface is appropriate for settings such as desktop use or for a wall-mounted display in a network operations center (NOC). The interface may prominently display a services health section with tiles for the aggregate KPI's indicating overall health for defined services and a general KPI section with tiles for KPI's related to individual service aspects. These tiles may display KPI information in a variety of ways, such as by being colored and ordered according to factors like the KPI state value. They also can be interactive and navigate to visualizations of more detailed KPI information.

SPLUNK® IT SERVICE INTELLIGENCE™ provides a service-monitoring dashboard visualization based on a user-defined template. The template can include user-selectable widgets of varying types and styles to display KPI information. The content and the appearance of widgets can respond dynamically to changing KPI information. The KPI widgets can appear in conjunction with a background image, user drawing objects, or other visual elements, that depict the IT operations environment, for example. The KPI widgets or other GUI elements can be interactive so as to provide navigation to visualizations of more detailed KPI information.

SPLUNK® IT SERVICE INTELLIGENCE™ provides a visualization showing detailed time-series information for multiple KPI's in parallel graph lanes. The length of each lane can correspond to a uniform time range, while the width of each lane may be automatically adjusted to fit the displayed KPI data. Data within each lane may be displayed in a user selectable style, such as a line, area, or bar chart. During operation a user may select a position in the time range of the graph lanes to activate lane inspection at that point in time. Lane inspection may display an indicator for the selected time across the graph lanes and display the KPI value associated with that point in time for each of the graph lanes. The visualization may also provide navigation to an interface for defining a correlation search, using information from the visualization to pre-populate the definition.

SPLUNK® IT SERVICE INTELLIGENCE™ provides a visualization for incident review showing detailed information for notable events. The incident review visualization may also show summary information for the notable events over a time frame, such as an indication of the number of notable events at each of a number of severity levels. The severity level display may be presented as a rainbow chart with the warmest color associated with the highest severity classification. The incident review visualization may also show summary information for the notable events over a time frame, such as the number of notable events occurring within segments of the time frame. The incident review visualization may display a list of notable events within the time frame ordered by any number of factors, such as time or severity. The selection of a particular notable event from the list may display detailed information about that notable event, including an identification of the correlation search that generated the notable event.

SPLUNK® IT SERVICE INTELLIGENCE™ provides pre-specified schemas for extracting relevant values from the different types of service-related event data. It also enables a user to define such schemas.

3.0. Skewing Scheduled Search Queries

FIG. 18 illustrates a block diagram of an example data intake and query system 1808 that includes a search query scheduling system 1810 and multiple search heads 210 in accordance with the disclosed embodiments. As shown, the data intake and query system 1808 includes, without limitation, search heads 210, indexers 206, and a search query scheduling system 1810 that communicate with each other over a network 1804. Each of the indexers 206 includes, without limitation, a data store 208. The search heads 210, indexers 206, and data stores 208 function substantially the same as corresponding elements of the data intake and query system 108 of FIG. 2 except as further described below. Network 1804 broadly represents one or more LANs, WANs, cellular networks (e.g., LTE, HSPA, 3G, and other cellular technologies), and/or networks using any of wired, wireless, terrestrial microwave, or satellite links, and may include the public Internet.

Each search head 210 of data intake and query system 1808 receives one or more search queries via search query scheduling system 1810. Each search head 210 analyzes each search query to determine what portion(s) of the search query can be delegated to indexers 206 and what portions of the search query can be executed locally by the search head 210. Each search head 210 distributes the determined portions of the search query to the appropriate indexers 206. Each search head 210 coordinates with peer search heads and with search query scheduling system 1810 to schedule jobs, replicate search results, update configurations, fulfill search requests, etc.

As further described herein, search query scheduling system 1810 schedules search queries for execution by search heads 210 and by search query scheduling system 1810. Search query scheduling system 1810 communicates with search heads 210 to dispatch each search query to one or more of the search heads 210 for execution. In operation, search query scheduling system 1810 and search heads 210 direct network traffic associated with search queries to indexers 206 via network 1804. Indexers 206, in turn, return network traffic associated with search results to search query scheduling system 1810 and search heads 210 via network 1804.

In some embodiments, search query scheduling system 1810 may be an instance of a search head 210. In such embodiments, each search head 210 may be capable of performing the functions of search query scheduling system 1810. Accordingly, each search head 210 may maintain a copy of the list of all search queries scheduled to execute within data intake and query system 1808. If the functions of search query scheduling system 1810 are to be transferred to a different search head 210, then the search head 210 may become the new search query scheduling system 1810 and begin to schedule search queries for execution by the search heads 210. Likewise, the current search query scheduling system 1810 may become one of the search heads 210 and cease to schedule search queries for execution by the other search heads 210. The current search query scheduling system 1810 is now described in further detail.

FIG. 19 is a more detailed illustration of the search query scheduling system 1810 of FIG. 18 in accordance with the disclosed embodiments. As shown, the search query scheduling system 1810 includes, without limitation, a processor 1902, storage 1904, an input/output (I/O) device interface 1906, a network interface 1908, an interconnect 1910, and a system memory 1912.

In general, processor 1902 retrieves and executes programming instructions stored in system memory 1912. Processor 1902 may be any technically feasible form of processing device configured to process data and execute program code. Processor 1902 could be, for example, a central processing unit (CPU), a graphics processing unit (GPU), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), and so forth. Processor 1902 stores and retrieves application data residing in the system memory 1912. Processor 1902 is included to be representative of a single CPU, multiple CPUs, a single CPU having multiple processing cores, and the like. In operation, processor 1902 is the master processor of search query scheduling system 1810, controlling and coordinating operations of other system components. System memory 1912 stores software applications and data for use by processor 1902. Processor 1902 executes software applications stored within system memory 1912 and optionally an operating system. In particular, processor 1902 executes software and then performs one or more of the functions and operations set forth in the present application.

The storage 1904 may be a disk drive storage device. Although shown as a single unit, the storage 1904 may be a combination of fixed and/or removable storage devices, such as fixed disc drives, floppy disc drives, tape drives, removable memory cards, or optical storage, network attached storage (NAS), or a storage area-network (SAN). Processor 1902 communicates to other computing devices and systems via network interface 1908, where network interface 1908 is configured to transmit and receive data via a communications network.

The interconnect 1910 facilitates transmission, such as of programming instructions and application data, between the processor 1902, input/output (I/O) devices interface 1906, storage 1904, network interface 1908, and system memory 1912. The I/O devices interface 1906 is configured to receive input data from user I/O devices 1922. Examples of user I/O devices 1922 may include one of more buttons, a keyboard, and a mouse or other pointing device. The I/O devices interface 1906 may also include an audio output unit configured to generate an electrical audio output signal, and user I/O devices 1922 may further include a speaker configured to generate an acoustic output in response to the electrical audio output signal. Another example of a user I/O device 1922 is a display device that generally represents any technically feasible means for generating an image for display. For example, the display device may be a liquid crystal display (LCD) display, CRT display, or DLP display. The display device may be a TV that includes a broadcast or cable tuner for receiving digital or analog television signals.

The system memory 1912 includes, without limitation, a search query scheduling program 1930, and a data store 1940. In operation, processor 1902 executes search query scheduling program 1930 to perform one or more of the techniques disclosed herein.

Search query scheduling program 1930 determines whether or not search query skewing is enabled. If search query skewing is not enabled, then search query scheduling program 1930 does not skew the scheduling of any search queries. If, on the other hand, search query skewing is enabled, then search query scheduling program 1930 computes a skew value for each search query that is eligible for skewing. The skew value for a particular search query is the amount of time the execution of the particular search query is delayed from the scheduled execution time for the search query. For example, four search queries that are scheduled to execute every minute could have skew values of 0 seconds, 15 seconds, 30 seconds and 45 seconds, respectively. In this example, the execution time of the four search queries would be skewed to the beginning of each minute, 15 seconds after the beginning of each minute, 30 seconds after the beginning of each minute, and 45 seconds after the beginning of each minute, respectively.

In addition, the skew value for each search query is subject to a maximum skew value, which, in general, may not be exceeded. Typically, the maximum skew value for a given search query is based on the chronographic schedule string (referred to herein as a “cron schedule string”). The cron schedule string determines how often a corresponding search query is scheduled to execute. For example, four cron schedule strings could specify that four corresponding search queries would be scheduled to execute once every minute, once every ten minutes, once every hour, or once every four hours. Correspondingly, the maximum allowable skew for these four search queries, based on these cron schedule strings, would be one minute, ten minutes, one hour, and four hours, respectively. The skew values for these four search queries would be limited so as not to exceed these respective maximum skew values.

In some embodiments, the maximum allowable skew may be further based on an allowable skew amount (referred to herein as an “allow skew setting”). The allow skew setting may be expressed as a percentage or as a specific duration of time. If the allow skew setting is expressed as a percentage, then the maximum allowable skew may be based on the cron schedule string multiplied by the percentage specified by the allow skew setting. In one example, the allow skew setting could be specified as 75%. The maximum allowable skew for four given search queries based on the cron schedule strings could be one minute, ten minutes, one hour, and four hours, respectively. The modified maximum allowable skew for these four given search queries would then be 45 seconds, 7.5 minutes, 45 minutes, and three hours, respectively. Alternatively, the allow skew setting may be expressed as a specific duration of time, such as five minutes or one hour. In such embodiments, the maximum allowable skew may be set to the duration of time specified by the allow skew setting, five minutes or one hour in this example, regardless of the cron schedule string. Finally, if the allow skew setting is set to zero (0′), then skewing is disabled for the corresponding search queries. An allow skew setting of 0 is a special case, where an allow skew setting of 0 does not need to be expressed as a percentage or with some other unit specifier that specifies a fixed duration.

In some embodiments, search query scheduling program 1930 may determine a maximum allowable skew based on both a global allow skew setting and per search query allow skew settings. In such embodiments, if the global allow skew setting is set to 0, then search query skewing may be globally disabled for all search queries. If, on the other hand, the global allow skew setting is set to any other valid setting, then search query skewing may be globally enabled for all eligible search queries. The final skew value for each search query may be computed by the techniques described herein. If the allow skew setting for a particular search query is set to 0, then the search query may be considered ineligible for search query skewing. Such a search query is not subject to search query skewing, even if the global allow skew setting is set to allow search query skewing.

Search query scheduling program 1930 also computes a hash value for the search query by applying a hash function to certain parameters associated with the search query. In some embodiments, the hash function may be computed as a function of any one or more of the name or title of the search, the textual description of the search, and the search string that specifies the parameters of the search. These three fields have a relatively high likelihood of being unique between one search query and another search query, but a relatively low likelihood of changing over time. Further, search query scheduling system 1810 and each search head 210 maintain a list of current search queries. Consequently, if the tasks of search query scheduling system 1810 are assigned to another search head 210, then the search head 210 can compute the same hash values for the search queries as computed by the previous search query scheduling system 1810.

After the maximum allowable skew and hash value are computed for each search query, search query scheduling program 1930 computes a final skew value for each search query. In some embodiments, search query scheduling program 1930 computes the final skew value according to Equation 1 below:

final skew value=hash value mod maximum allowable skew (Eqn. 1) where “mod” represents the modulo operation. One potential issue with employing the modulo operation to compute the final skew value is that the modulo operation exhibits a bias toward smaller numbers when the hash value is not evenly divisible by the maximum allowable skew. However, this bias effect can be minimized by choosing a hash function that produces hash values with a sufficiently high range. For example, a suitable hash function that minimizes this bias effect could produce hash values in the range of 0 to 2⁶⁴−1. With the disclosed approach, search query scheduling system 1810 and each search head 210 produce the same hash values, and consequently the same final skew values, for a set of search queries. As a result, search query scheduling system 1810 and the search heads 210 skew a particular search query by the same skew value without having to transfer skew values or other data between search query scheduling system 1810 and the search heads 210. As a result, the time between one execution of a particular search query and a consecutive execution of the same search query remains substantially the same, even when the tasks performed by the current search query scheduling system 1810 are transferred to a new search head 210.

In some embodiments, search query scheduling program 1930 may determine a skew tolerance based on the format of the corresponding cron schedule string. In such embodiments, search query scheduling program 1930 may determine that a search query has a relatively high skew tolerance if the corresponding cron schedule string corresponds to one of a particular set of formats. As described herein, search query scheduling program 1930 may determine that a search query has a relatively high search tolerance if the corresponding cron schedule string corresponds to one of five particular formats. These five formats may respectively indicate that the search query is scheduled to execute once every minute, once every N minutes, once every hour, once every N hours, or once every day, where N is an integer greater than zero. In some embodiments, the number of particular formats associated with a high skew tolerance may be less than five or greater than five, within the scope of the present invention.

Search query scheduling program 1930 may determine that a search query has a relatively low skew tolerance if the corresponding cron schedule string does not correspond to one of the five (or other number of) particular formats. For example, search query scheduling program 1930 could determine that a search query has a relatively low skew tolerance if the corresponding cron schedule string indicates that the search query is scheduled to execute at a specific time, such as the 11th minute of each hour or at 10:35 PM each day.

If a search query is determined to have a relatively high skew tolerance, then search query scheduling program 1930 may determine the final skew value for the search query based on the maximum allowable skew, as further described herein. If a search query is determined to have a relatively low skew tolerance, then search query scheduling program 1930 may determine the final skew value for the search query based on a fixed maximum allowable skew of relatively short duration. For example, search query scheduling program 1930 could determine the final skew value for a search query has a relatively low skew tolerance based on a fixed maximum allowable skew of sixty seconds. In this manner, search query scheduling program 1930 infers whether a particular search query has a relatively high skew tolerance or a relatively low search based on format of the cron schedule string corresponding to the search query.

In some embodiments, search query scheduling program 1930 may further employ a schedule windows technique, whereby a search query may be assigned a value that conveys to search query scheduling program 1930 that the search query is of lesser priority. In general, a schedule window provides an indication of how long the corresponding search query may be delayed. Search queries that do not include a schedule window are presumed to be of high priority and should execute on time during each period. Search query scheduling program 1930 may employ schedule windows to help ensure that search queries of greater priority have a better chance of executing on time and during each period, as specified by the corresponding cron schedule string. If, during a particular period, data intake and query system 1808 is resource-constrained to the point of being unable to execute all scheduled search queries to completion, then search query scheduling program 1930 may employ schedule windows to increase the likelihood that search queries of greater priority execute on time. As a result, search queries of lesser priority may not execute on time during a resource-constrained period.

By contrast, search query skewing, as described herein, distributes the dispatch and execution of equally important search queries out over a period of time, such as a minute or an hour. As a result, a large set of search queries is less likely to exhibit peak demand for system resources that temporarily overwhelms one or more components of data intake and query system 1808.

Search windows and search query skewing are independent features that may be employed separately or in conjunction with one another. When both search windows and search query skewing are concurrently employed, search queries are first skewed over a period, as further described herein. After skewing, those search queries that are scheduled to execute simultaneously are subject to any corresponding schedule windows related to those search queries. For example, if a large number of search queries are scheduled to execute at the 42nd second of a particular minute, then those windows with defined schedule windows would be considered to have lesser priority than search queries without defined search windows.

In one example, a first search query could have a schedule window set to zero. This first search query would be considered to not have a defined search window. Therefore, the search query would be considered to be of relatively greater priority and would be scheduled according to the search query skewing techniques described herein.

A second search query could have a schedule window set to ten minutes and be scheduled to execute once per minute. The second search query would be considered to be of lesser priority. This second search query would be scheduled to execute once per minute, but would be a candidate to defer execution if data intake and query system 1808 is unable to execute all search queries during a particular period. The second search query could be deferred additional periods until the second search query has been deferred for a duration of time equal to the schedule window. If the second search query has been deferred for a duration of time equal to the schedule window, then the schedule window of the second search query is temporarily set to 0 in order to increase the likelihood of execution during the next period.

Finally, a third search query could have a schedule window set to auto or automatic. The third search query would be considered to be of lesser priority. The schedule window for the third search query would be computed by subtracting the average duration of the last ten executions of the third search query from the period of the third search query. Therefore, if the average duration of the last ten executions of the third search query is twenty-five minutes and the third search query is scheduled to execute once per hour, then the schedule window for the third search query would be one hour minus twenty-five minutes, or thirty-five minutes.

In some embodiments, search query scheduling program 1930 may be subject to a maximum scheduled search percentage parameter. This maximum scheduled search percentage parameter may define a maximum percentage of the search capacity of data intake and query system 1808 that search query scheduling program 1930 may employ for scheduled search queries. Search query scheduling program 1930 may reserve the remaining search capacity for ad hoc search queries, where ad hoc search queries are one time search queries or occasional search queries that are not scheduled to execute periodically. For example, setting the maximum scheduled search percentage parameter to 50% would allow up to 50% of the search capacity of data intake and query system 1808 and reserve the remaining 50% of the search capacity for ad hoc search queries. Similarly, setting the maximum scheduled search percentage parameter to 70% would allow up to 70% of the search capacity of data intake and query system 1808 and reserve the remaining 30% of the search capacity for ad hoc search queries.

The maximum scheduled search percentage parameter is different than the search query skewing techniques described herein. In particular, the maximum scheduled search percentage parameter is an empirical value, typically set by a system administrator, that provides enough search capacity so that scheduled search queries are timely executed as often as possible, while reserving sufficient search capacity for a reasonable number of ad hoc search queries. If the maximum scheduled search percentage parameter is set too low, then scheduled search queries may not execute to completion during a particular period, even if data intake and query system 1808 has sufficient capacity to execute all scheduled search queries to completion. If, on the other hand, the maximum scheduled search percentage parameter is set too high, then peak demand occurring at the beginning of a period could still overwhelm the resources of data intake and query system 1808 and cause network data packet loss or other failure modes. By contrast, the search query skewing techniques described herein automatically skew search queries over an appropriate period of time without the need for empirical adjustment of a user-defined parameter, while increasing the likelihood that all search queries execute to completion accurately and on time.

FIGS. 20A-20B illustrate example chronographic schedule strings related to search queries in accordance with the disclosed embodiments. Each example chronographic schedule string (also referred to herein as a “cron schedule string”) illustrated in FIGS. 20A-20B includes five fields, labeled as “minute,” “hour,” “day,” “month,” and “day of week.” A numeric value in a particular field identifies a particular minute, hour, day, month, or day of week to execute the corresponding search query, as indicated by the numeric value. An asterisk ‘*’ in a particular field indicates that a search query is to execute every minute, hour, day, month, or day of week, according to the particular field that contains the asterisk. A value of the form “*/N” in a particular field indicates that a search query is to execute at or near the beginning of each N minutes, hours, days, months, or days of week, according to the particular field that contains a value in this form. In general, the number ‘N’ in the expression “*/N” is an integer greater than zero.

FIG. 20A illustrates example cron schedule strings 2002, 2004, 2006, 2008, and 2010 related to search queries associated with a relatively high skew tolerance. As shown, cron schedule string 2002 includes an asterisk ‘*’ in each field. Cron schedule string 2002 thereby indicates that the corresponding search query is to execute each minute of each hour of each day of each month. In other words, the search query corresponding to cron schedule string 2002 is to execute at the beginning of every minute.

Cron schedule string 2004 includes the value “*/N” in the minute field and an asterisk ‘*’ in each of the other fields. Cron schedule string 2004 thereby indicates that the corresponding search query is to execute every N minutes of each hour of each day of each month. In other words, the search query corresponding to cron schedule string 2004 is to execute at the beginning of every N minutes.

Cron schedule string 2006 includes the value ‘0’ in the minute field and an asterisk ‘*’ in each of the other fields. Cron schedule string 2006 thereby indicates that the corresponding search query is to execute at minute 0 of each hour of each day of each month. In other words, the search query corresponding to cron schedule string 2006 is to execute at the beginning of every hour.

Cron schedule string 2008 includes the value ‘0’ in the minute field, the value “*/N” in the hour field, and an asterisk ‘*’ in each of the other fields. Cron schedule string 2008 thereby indicates that the corresponding search query is to execute every N hours of each day of each month. In other words, the search query corresponding to cron schedule string 2008 is to execute at the beginning of every N hours.

Finally, cron schedule string 2010 includes the value ‘0’ in each of the minute and hour fields and an asterisk ‘*’ in each of the other fields. Cron schedule string 2010 thereby indicates that the corresponding search query is to execute at minute 0 and hour 0 of each day of each month. In other words, the search query corresponding to cron schedule string 2010 is to execute at the beginning of every day at midnight.

In sum, the cron schedule strings 2002, 2004, 2006, 2008, and 2010 correspond to search queries respectively scheduled to execute once per minute, once per N minutes, once per hour, once per N hours, or once per day. In some embodiments, search query scheduling system 1810 may infer that search queries corresponding to a cron schedule string in any of the formats exemplified by cron schedule strings 2002, 2004, 2006, 2008, and 2010 have a relatively high skew tolerance. Search query scheduling system 1810 may determine that the periodicity of such search queries is more important than executing such search queries at the beginning of each period. Stated another way, a search query corresponding to cron schedule string 2006 likely corresponds to a search query that should execute once per hour, but not necessarily at the beginning of each hour. Correspondingly, search query scheduling system 1810 may skew search queries corresponding to cron schedule strings in any of the five formats illustrated in FIG. 20A over the entire period specified by the cron schedule string. By contrast, search queries corresponding to cron schedule strings that are not in any of the five formats illustrated in FIG. 20A have a relatively low skew tolerance, as shown in FIG. 20B.

FIG. 20B illustrates example cron schedule strings 2052, 2054, 2056, 2058, and 2060 related to search queries associated with a relatively low skew tolerance. As shown, cron schedule string 2052 includes the value ‘11’ in the minute field an asterisk ‘*’ in each of the other fields. Cron schedule string 2052 thereby indicates that the corresponding search query is to execute at minute 11 of each hour of each day of each month. In other words, the search query corresponding to cron schedule string 2002 is to execute once per hour at the 11th minute of the hour.

Cron schedule string 2054 includes the value ‘0’ in the minute field, the value “22” in the hour field, and an asterisk ‘*’ in each of the other fields. Cron schedule string 2054 thereby indicates that the corresponding search query is to execute at hour 22 of each day of each month. In other words, the search query corresponding to cron schedule string 2054 is to execute once per day at the 10:00 PM, the 22nd hour of the day.

Cron schedule string 2056 includes the value ‘0’ in each of the minute and hour fields, the value “15” in the day field, and an asterisk ‘*’ in each of the other fields. Cron schedule string 2056 thereby indicates that the corresponding search query is to execute at day 15 of each month. In other words, the search query corresponding to cron schedule string 2056 is to execute once per month on the 15th of the month.

Cron schedule string 2058 includes the value ‘0’ in each of the minute, hour, and day fields, the value “1” in the month field, and an asterisk ‘*’ in the day of week field. Cron schedule string 2058 thereby indicates that the corresponding search query is to execute at month 1 of each year. In other words, the search query corresponding to cron schedule string 2058 is to execute once per year on January 1st.

Finally, cron schedule string 2060 includes the value ‘0’ in each of the minute, hour, day, and month fields, and the value “6” in the day of week field. Cron schedule string 2060 thereby indicates that the corresponding search query is to execute at day 6 of each week. In other words, the search query corresponding to cron schedule string 2060 is to execute once per week on Saturday (day 6).

In sum, the cron schedule strings 2052, 2054, 2056, 2058, and 2060 correspond to search queries respectively scheduled to a particular minute, hour, day, month, or day of week. In some embodiments, search query scheduling system 1810 may infer that search queries corresponding to a cron schedule string in any of the formats exemplified by exemplary cron schedule strings 2052, 2054, 2056, 2058, and 2060 have a relatively low skew tolerance. Search query scheduling system 1810 may determine that the particular time specified by cron schedule strings 2052, 2054, 2056, 2058, and 2060 is as important as the periodicity of such search queries. Stated another way, a search query corresponding to cron schedule string 2052 likely corresponds to a search query that should execute at, or relatively close to, 11 minutes after each hour. Correspondingly, search query scheduling system 1810 may skew search queries corresponding to cron schedule strings in any of the five formats as illustrated and exemplified in FIG. 20B over a relatively short time period, such as sixty seconds.

In some embodiments, cron schedule strings exemplified in FIGS. 20A-20B may be employed in conjunction with an allow skew setting to determine a maximum allowable skew for each corresponding search query, as now described.

FIG. 21 illustrates example allow skew settings 2102, 2104, 2106, 2108, 2110, and 2112 in accordance with the disclosed embodiments. In general, allow skew settings include a numerical value and a unit specifier. These unit specifiers include, without limitation, ‘%’ (percent), ‘s’ (seconds), ‘m’ (minutes), ‘h’ (hours), and ‘d’ (days). Alternative unit specifiers for seconds include, without limitation, “sec,” “second,” “secs,” and “seconds.” Alternative unit specifiers for minutes include, without limitation, “min,” “minute,” “mins,” and “minutes.” Alternative unit specifiers for hours include, without limitation, “hr,” “hour,” “hrs,” and “hours.”

Alternative unit specifiers for days include, without limitation, “day,” and “days.” The allow skew setting is employed to determine the maximum allowable skew for one or more corresponding search queries.

As shown in FIG. 21, allow skew settings 2102, 2104, and 2106 each include a numeric value followed by a ‘%’ unit specifier. In such case, the maximum allowable skew is computed by multiplying the allow skew setting by the period indicated by the corresponding cron schedule string.

Allow schedule setting 2102 includes the value ‘50’ followed by a ‘%’ unit specifier. Allow schedule setting 2102 thereby indicates that the maximum allowable skew is computed by multiplying 50% by the value indicated in the corresponding cron schedule string. The cron schedule string corresponding to allow schedule setting 2102 indicates a schedule of once per minute. Therefore, the maximum allowable skew for allow schedule setting 2102 is 50% of one minute, or 30 seconds.

Allow schedule setting 2104 includes the value ‘50’ followed by a ‘%’ unit specifier. Allow schedule setting 2104 thereby indicates that the maximum allowable skew is computed by multiplying 50% by the value indicated in the corresponding cron schedule string. The cron schedule string corresponding to allow schedule setting 2104 indicates a schedule of once per ten minutes. Therefore, the maximum allowable skew for allow schedule setting 2104 is 50% of ten minutes, or five minutes.

Allow schedule setting 2106 includes the value ‘75’ followed by a ‘%’ unit specifier. Allow schedule setting 2106 thereby indicates that the maximum allowable skew is computed by multiplying 75% by the value indicated in the corresponding cron schedule string. The cron schedule string corresponding to allow schedule setting 2106 indicates a schedule of once per hour. Therefore, the maximum allowable skew for allow schedule setting 2106 is 75% of one hour, or forty-five minutes.

Allow schedule setting 2108 includes the value ‘5’ followed by an ‘m’ unit specifier. Allow schedule setting 2108 thereby indicates that the maximum allowable skew is five minutes. The corresponding cron schedule string may be of any form illustrated in FIG. 20A.

Allow schedule setting 2110 includes the value ‘1’ followed by an ‘h’ unit specifier. Allow schedule setting 2110 thereby indicates that the maximum allowable skew is one hour. The corresponding cron schedule string may be of any form illustrated in FIG. 20A.

Finally, allow schedule setting 2112 includes the value ‘60’ without any following unit specifier. Therefore, allow schedule setting 2112 is considered to be an error, and skewing is disabled. Without a unit specifier, the cannot determine whether allow schedule setting 2112 is intended to indicate, for example, 60%, 60 seconds, 60 minutes, or some other value.

FIGS. 22A-22B illustrate example visualizations of system load before and after search query skewing is enabled in accordance with the disclosed embodiments.

In particular, FIG. 22A illustrates an example visualization of system load before search query skewing is enabled. System load represents any one or more technically feasible metrics related to usage of data intake and query system 1808 resources. These resources include, without limitation, compute processing capacity, input/output capacity, and total network bandwidth. As shown in FIG. 22A, a significant increase in load occurs at time 2204, corresponding to 10:11 AM at the beginning of the minute. Similarly, a significant increase in load occurs at time 2202, corresponding to 10:10 AM at the beginning of the minute. During the period between time 2202 and 2204, the system experiences relatively low load. In addition, a significant increase in load occurs at time 2206, corresponding to 10:12 AM at the beginning of the minute. During the period between time 2204 and 2206, the system experiences relatively low load.

FIG. 22B illustrates an example visualization of system load after search query skewing is enabled. As shown, times 2252, 2254, and 2256, respectively correspond to 11:00 AM, 11:01 AM, and 11:02 AM, at the beginning of each of these minutes. A moderate increase in load is indicated at time 2252 and time 2254. However, FIG. 22B indicates that the load is balanced over the entire period between time 2252 and time 2254, as compared with the period between time 2202 and 2204 of FIG. 22A. Similarly, FIG. 22B indicates that the load is balanced over the entire period between time 2254 and time 2256, as compared with the period between time 2204 and 2206 of FIG. 22A. Correspondingly, the likelihood that data intake and query system 1808 experiences excessive load, resulting in network data packet loss or other failure modes, is reduced when skewing of search queries is enabled (FIG. 22B) relative to when skewing is not enabled (FIG. 22A).

FIG. 23 is a flow diagram of method steps for skewing search queries in accordance with the disclosed embodiments. Although the method steps are described in conjunction with the systems of FIGS. 1-2, 10-11, and 18-19, persons of ordinary skill in the art will understand that any system configured to perform the method steps, in any order, is within the scope of the present invention.

As shown, a method 2300 begins at step 2302, where a search query scheduling program 1930 executing on a search query scheduling system 1810 classifies a search query based on a corresponding cron scheduling string. If the cron scheduling string is in one of five particular formats that indicates the search query is scheduled for execution once every minute, once every N minutes, one every hour, once every N hours, or once per day, then the search query scheduling program 1930 classifies the search query as having a relatively high skew tolerance. If the cron scheduling string is in format that is different from one of these five particular formats, then the search query scheduling program 1930 classifies the search query as having a relatively low skew tolerance.

At step 2304, the search query scheduling program 1930 computes a maximum allowable skew amount for the search query scheduled to execute on a data intake and query system 1808. If the search query is classified as having a relatively high skew tolerance, then the search query scheduling program 1930 computes the maximum allowable skew amount based on a cron scheduling string associated with the search query. In general, the search query scheduling program 1930 sets the maximum allowable skew amount as the time between one scheduled execution of the search query and a consecutive scheduled execution of the same search query. If the search query is classified as having a relatively low skew tolerance, then the search query scheduling program 1930 sets the maximum allowable skew amount to a relatively low fixed value, such as sixty seconds.

At step 2306, the search query scheduling program 1930 modifies the maximum allowable skew amount based on an allow skew setting. If the allow skew value specifies a percentage value, then the search query scheduling program 1930 multiplies the maximum allowable skew by the percentage value to generate the modified maximum allowable skew amount. If the allow skew value specifies a specific duration of time, then the search query scheduling sets the modified maximum allowable skew amount as the specific duration of time.

At step 2308, the search query scheduling program 1930 computes a hash value associated with the search query. The hash value is based on one or more attributes of the search query that are relatively likely to be unique between one search query and another search query, and are relatively unlikely to change over time. For example, the search query scheduling program 1930 could compute a hash value for the search query based on any one or more of the name or title of the search, the textual description of the search, and the search string that specifies the parameters of the search.

At step 2310, the search query scheduling program 1930 computes a final skew amount for the search query. The search query scheduling program 1930 may compute the final skew value as: final skew value=hash value mod maximum allowable skew, where “mod” represents the modulo operation.

At step 2312, the search query scheduling program 1930 adjusts the priority of the search query based on a schedule window. If the schedule window for the search query is set to zero, then the search query would be considered to be of relatively greater priority and would be scheduled according to the search query skewing techniques described herein. If the schedule window for the search query is set to a particular duration, then the search query would be considered to be of lesser priority. The search query would be a candidate to defer execution for a duration not to exceed the duration of the schedule window. If the schedule window for the search query is set to auto or automatic, then the third search query would be considered to be of lesser priority. The schedule window for the search query would be computed by subtracting the average duration of the last ten executions of the third search query from the period of the third search query. Therefore, if the average duration of the last ten executions of the third search query is twenty-five minutes and the third search query is scheduled to execute once per hour, then the schedule window for the third search query would be one hour minus twenty-five minutes, or thirty-five minutes. The method 2300 then terminates.

In sum, the dispatch and execution times for scheduled search queries in a data intake and query system are skewed so that the scheduled search queries do not all execute at the same time. Each search query is delayed by a computed amount. A maximum allowable skew amount is determined based on the frequency of execution of the search query, as defined by the chronographic scheduling string corresponding to the search query. The maximum allowable skew amount may be modified by multiplying the maximum allowable skew by a percentage value specified by an allow skew setting. Alternatively, the allow skew setting may specify a specific duration that defines the maximum allowable skew amount. A hash value is computed for each search query based on certain parameters related to the search, such as the name or title of the search, the textual description of the search, and the search string that specifies the parameters of the search. A final skew value for each search query is computed based on the corresponding hash value and maximum allowable skew amount.

At least one advantage of the disclosed techniques is that search queries scheduled to occur simultaneously are skewed over a period of time. As a result, the demand for computing and network resources is not concentrated at certain points in time, but rather is distributed over a period of time. By distributing the demand for computing and network resources over a period of time, the likelihood of network data packet loss or other failure modes due to the excess demand is reduced relative to prior approaches.

The descriptions of the various embodiments have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Aspects of the present embodiments may be embodied as a system, method or computer program product. Accordingly, aspects of the present disclosure may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “module” or “system.” Furthermore, aspects of the present disclosure may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon.

Any combination of one or more computer readable medium(s) may be utilized. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

Aspects of the present disclosure are described above with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the disclosure. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions/acts specified in the flowchart and/or block diagram block or blocks. Such processors may be, without limitation, general purpose processors, special-purpose processors, application-specific processors, or field-programmable gate arrays.

The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

While the preceding is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. 

What is claimed is:
 1. A computer-implemented method, comprising: associating a first set of queries with a first skew tolerance, the first set of queries scheduled to be performed during a first period, wherein the first skew tolerance is based on a duration of the first period; and rescheduling a first subset of search queries included in the first set of queries by skewing the first subset of search queries over a first portion of the first period based on the first skew tolerance.
 2. The computer-implemented method of claim 1, further comprising: associating a second set of queries with a second skew tolerance, the second set of queries scheduled to be performed during a second period, wherein the second skew tolerance is based on a duration of the second period; and rescheduling a second subset of search queries included in the second set of queries by skewing the second subset of search queries over a second portion of the second period based on the second skew tolerance.
 3. The computer-implemented method of claim 1, wherein the first portion of the first period is based on a maximum skew amount associated with the first subset of search queries.
 4. The computer-implemented method of claim 1, wherein the first portion of the first period is based on a maximum skew amount associated with the first subset of search queries, and further comprising modifying the maximum skew amount based on an allow skew setting.
 5. The computer-implemented method of claim 1, wherein the first portion of the first period is based on a maximum skew amount associated with the first subset of search queries, and further comprising modifying the maximum skew amount by multiplying the maximum skew amount by a percentage value associated with an allow skew setting.
 6. The computer-implemented method of claim 1, wherein the first portion of the first period is based on a maximum skew amount associated with the first subset of search queries, and further comprising setting the maximum skew amount to a fixed value associated with an allow skew setting.
 7. The computer-implemented method of claim 1, further comprising computing a hash value for a first search query included in the first subset of search queries based on parameters associated with the first search query.
 8. The computer-implemented method of claim 1, further comprising computing a hash value for a first search query included in the first subset of search queries based on parameters associated with the first search query, wherein the parameters associated with the first search query include at least one of a title associated with the first search query, a description associated with the first search query, and a search string associated with the first search query.
 9. The computer-implemented method of claim 1, further comprising computing a skew value associated with a first search query included in the first subset of search queries.
 10. The computer-implemented method of claim 1, further comprising computing a skew value associated with a first search query included in the first subset of search queries, wherein the skew value is computed as a hash value associated with the first search query modulo a maximum skew amount associated with the first search query.
 11. The computer-implemented method of claim 1, further comprising adjusting a priority associated with a first search query included in the first subset of search queries.
 12. The computer-implemented method of claim 1, further comprising adjusting a priority associated with a first search query included in the first subset of search queries, wherein the priority associated with the first search query is adjusted based on a schedule window that indicates an allowable deferral period associated with the first search query.
 13. The computer-implemented method of claim 1, wherein a first search query included in the first subset of search queries is directed to a set of events, and each event included in the set of events includes raw machine data and an associated time stamp timestamp derived from the raw machine data.
 14. The computer-implemented method of claim 1, wherein a first search query included in the first subset of search queries is directed to a set of events, and each event included in the set of events includes raw machine data from sources associated with a first component in an information technology (IT) environment.
 15. The computer-implemented method of claim 1, further comprising: executing a first search query included in the first subset of search queries, wherein the first search query is directed to a set of events; and during execution of the first search query, applying a late-binding schema to event data associated with the set of events.
 16. The computer-implemented method of claim 1, further comprising: executing a first search query included in the first subset of search queries, wherein the first search query is directed to a set of events; and during execution of the first search query, applying an extraction rule to extract a value for a first field associated with the event data.
 17. A non-transitory computer-readable storage medium including instructions that, when executed by a processor, cause the processor to perform the steps of: associating a first set of queries with a first skew tolerance, the first set of queries scheduled to be performed during a first period, wherein the first skew tolerance is based on a duration of the first period; and rescheduling a first subset of search queries included in the first set of queries by skewing the first subset of search queries over a first portion of the first period based on the first skew tolerance.
 18. The non-transitory computer-readable storage medium of claim 17, further comprising: associating a second set of queries with a second skew tolerance, the second set of queries scheduled to be performed during a second period, wherein the second skew tolerance is based on a duration of the second period; and rescheduling a second subset of search queries included in the second set of queries by skewing the second subset of search queries over a second portion of the second period based on the second skew tolerance.
 19. The non-transitory computer-readable storage medium of claim 17, wherein the first portion of the first period is based on a maximum skew amount associated with the first subset of search queries.
 20. The non-transitory computer-readable storage medium of claim 17, wherein the first portion of the first period is based on a maximum skew amount associated with the first subset of search queries, and further comprising modifying the maximum skew amount based on an allow skew setting.
 21. The non-transitory computer-readable storage medium of claim 17, wherein the first portion of the first period is based on a maximum skew amount associated with the first subset of search queries, and further comprising modifying the maximum skew amount by multiplying the maximum skew amount by a percentage value associated with an allow skew setting.
 22. The non-transitory computer-readable storage medium of claim 17, wherein the first portion of the first period is based on a maximum skew amount associated with the first subset of search queries, and further comprising setting the maximum skew amount to a fixed value associated with an allow skew setting.
 23. The non-transitory computer-readable storage medium of claim 17, further comprising computing a hash value for a first search query included in the first subset of search queries based on parameters associated with the first search query.
 24. A computing device, comprising: a memory that includes a search query scheduling program; and a processor that is coupled to the memory and, when executing the search query scheduling program, is configured to: associate a first set of queries with a first skew tolerance, the first set of queries scheduled to be performed during a first period, wherein the first skew tolerance is based on a duration of the first period; and reschedule a first subset of search queries included in the first set of queries by skewing the first subset of search queries over a first portion of the first period based on the first skew tolerance.
 25. The computing device of claim 24, wherein the processor is further configured to: associate a second set of queries with a second skew tolerance, the second set of queries scheduled to be performed during a second period, wherein the second skew tolerance is based on a duration of the second period; and reschedule a second subset of search queries included in the second set of queries by skewing the second subset of search queries over a second portion of the second period based on the second skew tolerance.
 26. The computing device of claim 24, wherein the first portion of the first period is based on a maximum skew amount associated with the first subset of search queries.
 27. The computing device of claim 24, wherein the first portion of the first period is based on a maximum skew amount associated with the first subset of search queries, and wherein the processor is further configured to modify the maximum skew amount based on an allow skew setting.
 28. The computing device of claim 24, wherein the first portion of the first period is based on a maximum skew amount associated with the first subset of search queries, and wherein the processor is further configured to modify the maximum skew amount by multiplying the maximum skew amount by a percentage value associated with an allow skew setting.
 29. The computing device of claim 24, wherein the first portion of the first period is based on a maximum skew amount associated with the first subset of search queries, and wherein the processor is further configured to set the maximum skew amount to a fixed value associated with an allow skew setting.
 30. The computing device of claim 24, wherein the processor is further configured to compute a hash value for a first search query included in the first subset of search queries based on parameters associated with the first search query. 